Testing - Does Seating Depth Make a Difference?
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- čas přidán 1. 06. 2024
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Kelbly's is amazing! I'm a member at their range, and they are just downright good people. Family folks willing to help a stranger. I was in need of a little help getting a chassis fit on a rifle. Not knowing the"level" of what went on behind the shop doors, i approached with no expectations. Not only was i greeted with enthusiasm, but they took a quick look at my issue and disappeared with my rifle. I quickly learned details of what went on there, and I'm certain he could see the light click on in my eyes. He offered me a tour of the shop (which i jumped at the opportunity) and he showed me every step start to finish! Anytime i had a question, the guy performing the operation was proud to take a moment and explain. I've got a woodworking background, so watching them transform chunks of steel into a finely machined work of art was VERY fascinating! After my tour, we we're met back at the front office with my newly fitted rifle to chassis. I was then told there was no charge for the help. I wasn't raised that way, and left double what i thought might cover it. Simply down to earth, absolute good people!
I love this.
I love that someone is doing these tests, I love how "in the weeds" this is getting. I love the that he literally says the exact same thing I say after nearly every range trip... "I'm left with more questions than answers. "
I always felt like an idiot because I'd follow the instructions, I'd do the tests the way they say, I'd base my load on that data, load 25 more that same way, go out the next day and shoot completely differently. I'd ask 5 different people and get 5 different answers. I'm left wondering what REALLY matters... you ask a bench rest guy and EVERYTHING matters... you ask an f class guy and they think the bench test guys go too far, but they also measure the volume of each case because they're convinced that matters. Then you hear prs shooters say they don't even do seating depth tests because it doesn't matter THAT much... what can anyone believe?
I want to do these kinds of tests, but I don't have the time, money, or equipment to do them right. I will be following this series closely. I love the hard data. I love that you talk about things like "standard deviation" and "statistically significant" data. These are terms and methods used by the scientific community to figure out IF there was a change, but also how impactful or noticeable that change is, and if their distribution is reliable. I took a statistics class in college, and I learned how to calculate all of these, but I have since forgotten. I'd have to pull up a text book to refresh my memory on the details, but I remember the general concepts, and this research is directly in line with what I learned.
Please keep going with the same attention to detail.
I'm the guy who have shot a one-inch Group at 100 yd what happened quite happy. I tested some different ammo and saw that some ammo just shoots better than others. I started measuring stuff and then started testing. I saw that there was some noticeable tightening of groups. I decided to buy a good Barrel. Repeat it the same tests and saw that the good Barrel basically mirrored the same thing except the groups were all tighter. I did a powder test at the same seat depth, one bullet each and did two sets of tests that way. I recorded the Target so I knew what was hitting where. They all shot good but what I found was a little bit lower than Max seem to hit in the same area before it started to walk point of impact. I took a powder charge that was on the top end of what I thought would still group okay. All I did was load them .04 longer. Made a big difference. I have never shot a .34moa group before. I was now beginning to see how I shot the rifle would make a difference in the groups, where as I would never know before
Í
OK, I knew I didnt know anything...... this confirms it !
Its just more proof that small sample sizes are misleading and if people don't understand why they need to dedicate the time to understand statistics
Dang I don’t know didly.
Ok here 2. Can kind of understand John lott " more guns less crime" what i don't understand is if I can hole em 50% each in can I call that good .? I know : no ok WHY NOT? SERIOUSLY
I’m confused
@@newerest1 "shoot out your barrel to find the perfect load"
Hello from down in New Zealand. I've been watching your videos for a long time . . . . This one is among the most usefull and profound you've produced. Thank you!
Thank you for sharing Keith. I love the way you apply science to your testing and show the importance of statistical significance.
This is fantastic! It reminds me of my Ph.D. dissertation where the conclusion was (paraphrasing), "the math works, the process works, but it's just not efficient and no one knows why." Granted, that was for a couple electrochemical reactions to convert molecules from oxides to hydrides... but I totally feel the pain all over again of having more questions than answers.
I had PhD once I tried everything to get rid of it but no matter what the doctor gave me didn't work, then it went away over time
Things I can confidently take away from this video: your gun shoots very well
Load development always reminds me of this quote: We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things.
This is one of the very best Shooting / Loading videos ever produced. Pure science without bias toward any Caliber / Rifle Mfg./ or Bullet Mfg. Love this Thank You. Lenny
Thank you for sharing!! Also, thanks for detailed explanations about the testing format.
Thank you very much for this valuable research.
Fantastic video, greatly appreciate your efforts on this one and the great break down, even if there weren't any solid conclusions.
Thank you. I’m relatively new to reloading. Knowing I’m not the only one trying to work this our help a lot.
The more I learn, the better golf looks...............!
😂
The key to load development is to not put too much emphasis on any one or two stats. That tiny group at 100 yds for 3 or 5 shots may not tell you much at distance. Thanks for taking us down the bunny hole with you Keith!
No ads! What a legend :D Great video also!
Even when I don’t understand all of what you’re talking about I find it interesting and entertaining to watch. I do learn a lot though, and as a new precision shooter and one who’s reloading, thank you for doing things I would never even think of.
Awesome video, keith!
So we discovered consistency matters most.
This has made the inconclusive seating depth test I did yesterday, more inconclusive haha. Joking - I really enjoy your content.
Great video. I’ve decided if you pick a good bullet with an appropriate powder you’ll be fine. With big enough groups things start to look a lot the same.
Always great content, thank you.
Wow. Now we have to contend with Group Center Wander. 30 years as the nut behind the bolt and I was oblivious on a conscious level to this. Thank you for the time, money and effort you have spent on this test.
Great work! This is exactly why my 100 yard stuff is just to get some "maybe" loads. Then hit 600 for testing/fine tuning and eventually 1k tuning. What's really fun is sometimes my 600 best load and my 1000 best load aren't the same... How fun is that? Ultimately there is always just a bit of voodoo involved due to how many variables exist. Love watching the channel and seeing the science behind the magic.
Thanks for sparing us the ads👊🏻
Great video - fun and interesting stuff!
Really outstanding testing there. I’m glad that somebody out there is thinking about group size and statistical significance. These days I don’t worry too much about seating depth as long as I’m shooting hybrid bullets. The main thing I do when reloading is make sure that the seating depth is as consistent as I can make it. My personal thought is that variability in the seating depth is way more significant than the actual depth itself.
Without reinventing the wheel simple ram and cram work best for me. My experience was best to neck size only to max .001-.002 tension, load longer than the lands, then single feed in my 700. The caming of the bolt insures the case shoulder is against the chamber datum line case to case same, and the bullet "jump" is zero insuring exact same cartridge to cartridge without calculating throat erosion. Works for me and simple consistency...
More questions than answers usually means that you’re on the right track. The world is vast and infintismally small. Isn’t that great? Excellent video.
I think you just validated something Hornady presented data and outside expert commentary on a few months ago.
There's SO much we shooters 'know' that's just not so. OTOH, confidence materially and demonstrably improves performance, so one doesn't go trying to undermine oneself.
I guess the big question is; at what point do you stop splitting hairs? My answer would be, when you stop having fun. I love seeing the research because someone else is putting in the work.
Great analysis, and I concur with your conclutions.
It's competition. You stop when you win and when the competition stops trying to beat you.
Great video, thank you Sir👍
Great video. Thanks for explaining and proving the sample size that we need to be working with.
Absolutely fantastic.
Great video! The number one most important thing to me when im doing seating tests is windflags. To me its pointless without.
Yep, as per Gödel's theorem there are true statements in the realoading theory which cannot be proved.
yet
If you could have seen the smile on my face when you said, "We are closer to proving they are all the same, not different". Nature is perfect, nothing else. Some think 1ft is close, some 0.25", others won't settle for less than 0.001" and most who state, 0.0004" might be accurate in what something should be, but they have no clue how to measure, (guarantee) it. Or worse, you see a shaky table with a Starrett Vernier Height Gage. Tolerance is as misunderstood as monetary policy. In other words, everyone is an expert, (at spitting the rhetoric), until it isn't. (Argentina, Rome, Japan). Much respect for what you do, so refreshing to see people taking things to the nth degree. "If you torture the data long enough, it will confess", but unicorns still don't exist. Try, test, break and prove. Don't vehemently spit rhetoric from other sources. If I haven't done it, tried it, lived it, built it, broke it, tested it, everything else is hearsay, rhetoric or logical fallacy. TEST, TEST, TEST, question the data and RETEST, RETEST, RETEST. The goal of science is not to find a final answer, but to ask better questions. long time subscriber... Great content, please keep it up. Will try to be better on the likes, sorry. (.284 fan, 7mm-08 and 280AI)
So well said sir.
Thanks!
Thank you!
Biggest thing you’d didn’t mention that you have to consider is variances in case head space and case trimming which has a large impact on seating depth depending on the dies and case trimmer you use.
How does case trim length effect seating depth?
The C.O.A.L is measured from the case base as is C.B.T.O.
Headspace is what it is. Everyone seems to be able to get it +/- 0.001 which I don't think makes much if any measurable difference. Even if we could measure the difference, there's nothing to be done about it anyway.
good explanation! somehow I missed your genial diagram with grouped box plot with ED SD and average values for each depth.
I miss the Biden Harris ads that usually bracket my favorite firearms CZcamsrs. I do love irony.
Just keep in mind, under the Biden administration, NFA approvals are the fastest they’ve been in 15 years.
I am a scientist and appreciate your hypothesis and the fact instead of definitive answers you created more questions. Isn't science great? LOL, good job
What video is the one where you mention diferent bullet profiles and the seating dept that they favor?
Nice video and you confused me. ?what would happen if you shoot a 33 round control group of factory match to set the base numbers? Would that be relevant or a waste?
Okay, let's do this. Subscribed, bell rang, commented, liked, upvoted, shared .... may the algorithm gods smile favorably upon your channel.
The numbers are science if you ask me. They are controlled enough for me to find the testing valid. The only question is the question of repeatability.
I assume that if we were to do this experiment again a second time, (which I would love for research purposes of course) that the small sample size groups would have completely different results because of the small sample size variability. I also believe that the large 33 shot groups would probably be quite similar.
I recently was testing the speers grand slam in my hunting rifle, the speers data listed a seating depth of 2.685, i could not get these to group, we're talking 3-4 inches at hundred yards. In a last dig effort i measured these bullets to my barrels lands, which was 2.848, this was such a huge jump that i loaded them to 2.775 and got them to group sub MOA with two different powders. Seating depth plays a huge roll. IMO
Nice. As a scientist often employing statistical analysis on small and large data sizes I love this particularly your statement about your lack of significance in proving a difference from the null hypothesis. One might assume its for a lack of power or data size but perhaps not as the distribution shapes in 2d are quite different. Thank you. Your experiment here seems to assume that for each loading you actually achieved the same seating depth for each round. If you could have I'll bet there is some movement there and differences in variation vs your different target depths, meaning I'd expect greater variation with deeper seating depth. . I'll also bet on variation in seating neck tension?. How precise are your depth measurements and inside neck diameter? With different distribution shapes, standard statistical models may struggle. If you had the data of high precision seating depth one could plot vector values angle and distance from center vs that. Probably out of scope though.
Another variable people often don't think about when measuring group size/mean radius from the center of the bullseye or the corner of the square for this instance is that I can almost guarantee the crosshairs were not in the position you are measuring from when the shot broke for every single shot. As steady as you can hold the crosshairs on center, there is going to also be variance from that which is typically not accounted for.
Yes, that is a good point. Shooter performance is an expected source of noise in a test like this, just like conditions are.
First of all I’m a firm believer in seating depth doesn’t matter, but only if you are using hybrids and tangent style projectiles.
Things to remember. He was using hybrid projectiles. Which Litz has stated in his science is not affected by seating depth as much as secant/vld profile projectiles.
Outstanding video!
Thank you sir!
Liked & Sub'd.
Run the median values(median radius and median group sizes and appropriate SD and ES)and see if the story changes... and an ANOVA test. In all my research lab experience, when sample sizes were low, median values were the way to go because they are resistant to outliers, good and bad ones. Anyway you slice it 33 holes is a small sample size out of the total "population". Not a dig at you, it's more than most people do, and reality dictates that unless you have someone feeding you time, money, components, and barrels, getting legitimate large sample size of everything you want to test is not even close to practical. Anyway, try the medians and anova on what you already have, thanks for the info and keep up the good work.
The biggest problem is with "proper" large sample size for cartridge load tests is the limitation of barrel life, and the fact that the barrel's behavior changes over time. There is a sweet spot after proper break-in and before accuracy fall-off that is probably not-quite big enough for a single proper large sample size. So any large sample size tests can only be a single run of a single variable on a single barrel. And that is essentially meaningless if we want to compare two or more options.
So we are stuck with smaller sample sizes if we want to compare two or more options.
@@nathanbailey9153 yeah, that's pretty much my point. You run into similar stuff in research labs. Where, due to the nature of something or something beyond your control, or practical constraints, you're gonna have small sample sizes. The way we delt with that was median values and anova tests. Sample median usually approaches the true population mean, before the sample mean does. This is because the median is resistant to outliers, and the mean has to have a sample size larger enough to overcome the outliers.
It is a constant challenge trying to be better especially when you almost have it down. Nothing seems to be a 100% constant in reloading. Most everything can change group size and when you change one thing it is more than one thing. Bullet length effects case capacity as well as bullet jump or jammed in the lands. Have fun to all there are always more questions than answers. It's always fun seeing what others are trying and what works for them.
Great video - I am curious as to what made you pick setting 3 in the first instance before this test...what did you see that made you go setting 3 direction?
Setting 3 was a result on several barrels worth of experience. I look at how the rifle responds to conditions and how it aggs.
@@winninginthewind can you take us through that sometime?
The nearest thing too factual testing we have is from hornady but they’re obviously using Hornady brass and bullets. I know from experience that the components aren’t precise enough too even show a difference in small adjustments too the load. I want too see Capstone or Berger do some large sample size testing.
Having shot silhouette competition for years I've found that some cases will not shoot. Therefore after I have prepped all of my cases I go to the range and any round that shoots outside of my group goes into my junk brass. I've shot many 1/16 inch groups following this procedure. I feel the brass is the most important part of the reloading procedure.
Even though no actual jump numbers were given in this video, it sounds very similar to Mark Gordon’s study from a few years ago written about on the Precision Rifle Blog. It seems to confirm that the micro results of best 3 and 5 shot groups don’t match the macro results of consistency of group size and POI over a larger sample size. Typically a bullet jump of .050 - 0.100 yields better large sample consistency even though .010-.030 might give you tinier 5 shot groups.
I have a Ruger77 MkII in 300WM. At best with factory ammo 2 MOA maybe a tad under. I loaded 20 rounds Starting at factory dimensions and did 5 groups .005" steps and found the sweet spot thankfully in my third group a full .015" longer than factory. I'll take that experience to the bank as the simple hunter that I am.
Hi Keith, Love you video and ground mat. Where's the mat from please? Cheers, LD girl from Sydney OZ
That one was made by Creedmoor Sports here in the US.
Also, bullets are different and will shoot distinct patterns depending on how they are made. Lead tamp just a liftle off center and you will get 3&2 groups. Boatail off a bit. 4&1 groups. Point being, you are holding the bullets as a known constant when they are not, especially at the differences you are trying to detect.
There it is. Combine that with tiny differences in ogive and jacket thickness, as well as atmospheric differences from the previous shot, and minute amounts of equipment wear. Now at least I have my excuse.
Now to perform the same test at 1,000yds. I really liked this video. I did a similar test with only 2 loads at 1,000yds and 20 rounds of each load with my 223 and the smallest 100yd group was not the winner for sure.
Keith , great video I’m a friend of Michael’s who you mentioned.
I don’t understand why you say the group center shifted , I think it is much more sensible to calculate the relative center for each load then take all data from there it just streamlines the result. If you only look at it that way I think the data will show the statistical samples are indistinguishable.
You are correct. No matter which group center I use, there is nothing statistically significant about the very small differences in the samples that cannot be the result of random chance. The moving center is a concern for long strings of fire at long range. It is easier for the shooter to correct for wind conditions without group center movement, but even that observation was only an anecdotal one. A lot more testing would be needed to clarify and validate this as a behavioral pattern.
Yes, it's just another form of being fooled by random noise in the data. Load development/tuning beyond a certain point may be a myth, and we are just engaging in voodoo based on noisy samples.
Science entirely does work by proving or disproving a hypothesis, but it has to be done in a way that removes tester/test bias and confounding variance
I'm not by any means, an F-class shooter, but I would venture to think that bullet jump plays a roll in how concentric the bullet is going to be when it hits the rifle lands. The farther the jump, the more the variance. When I reload, I measure and weight every component and group them to the least variance. Also I seat bullet to slightly touch the lands to eliminate bullet jump. That has given me great results.
Be careful with this, for as the throat of your rifle erodes that slight touch will become a slight gap; you'll need to adjust your length regularly to maintain what you've got
Slightly touching is the most erratic seating depth you could choose. If the CBTO is .001 shorter the pressure spike will be wildly different than if the CBTO is .001 longer than normal. Not good.
@@DanielReyes-hz1qk Erik Cortina, current world F-Class champion, states in a full video that "chasing the lands" is not the key to accuracy or consistency. His concept is that you are trying to achieve a consistent pressure-curve within the case and post-ignition barrel volume for every shot. internal case volume ( loaded) depends on an accurate powder amount and an accurate bullet base position to ensure identical ignition. Initial seating depth is mostly to see what gives the best overall basic accuracy and will function in the action.. After that, you keep that same seating depth for the life of that barrel, all other components being equal and identical.
@@scottcrawford3745 I'm aware of that, and have seen the video. But that doesn't apply to the person above using a load that just touches the lands; that pressure curve is going to change dramatically the moment those rounds no longer touch the lands. He mentions this exact scenario, if not in that video then in another
@@DanielReyes-hz1qk The Number 2 guy in the world uses a .020 jam into the lands as his seating length... not sure of the pressure game he's playing.
My bullets are Hexagonal Boron Nitride coated, So I have a little more leeway with friction vs. jump than some.
If you're watching your brass/ primers and paying attention to the signs, I'm sure it's reasonably safe, as long as you're not at the very threshold of max pressure. After all: they only need to punch paper.
How much did air temp change during your test,barometric pressure, your load, powder type, etc… there are many things that are controlled but are they? Was there a small breeze? Did one bullet have a small deformity? The brass, was it new or how many firings? What primer type? Seating depth of primers? Did you clean your barrel between each firing? I know you know all of this? I’m quite impressed with your test and attention to detail, as well as your analysis of data seems on point. But in theory you’d have to repeat the whole test 30 plus times which is impossible under the same conditions.
More evidence tuners dont really work, especially when people only shoot 2-3 shot groups, great video 👍
Where can I get that hoodie?
This test does anecdotally support the general belief in High Power / Service Rifle circles where it is accepted that the highest scoring loads often are not the ones with the smallest SD. The load that scores best, scores best. To confound predictions even more, the case can be made that some fractional amount of intrinsic error is not always a bad thing. It would seem that at some point we get within the margin of error and start chasing results that we cannot guarantee given the variables that we cannot control. Worse yet, your ammo may get so accurate that you lose the margin of forgiveness that was benefitting you.
Statistically, intrinsic error in the cone of fire can help you as often as it hurts you. Sounds crazy, but here's a great video from Konrad (HP legend) showing just that: czcams.com/video/wBIligz1NlU/video.htmlsi=E74e0MVzEKvZKmt7
I was thinking more about this overnight. I wonder…we know the Hybrid is a relatively tolerant bullet. It’s why we like it. However, how does barrel wear play into it? How about bullet variance? Lot to lot variance? With so many variables, could regression analysis be helpful in determining where to place our focus?
Bullet seating depth and free bore seem to be the reason why one another are hot topics.
If you get the free bore you desire at that point should it just really be at the mercy of powder primer with a constant being the published seating for the load in the reloaded bible?
Where did you get the barrel temperature stickers? I have some that I got from McMaster, but they don't stick as well as they could on a cylinder.
That one is from McMaster-Carr. You are correct, they don't stick to small cylinders very well.
@@winninginthewind Thanks. I'll have to take a look through their stuff again.
Yes it does, if you don’t have a barrel weight/length harmonics adjustment. Both is best.
A recommendation: consider performing a 2-way ANOVA since there are factors that could affect another factor, ie: barrel temperature with x.
Hey Keith, quick question: how "far apart" were the 3 different seating depths you selected for your testing?
At 5:25 you asked if you "can do seating depth testing in much bigger increments" and I'm just curious what the total delta CBTO (in inches) was for your 3 loads?
Load #1 was .009" from load #2 and .015" from load #3.
Crimp pressure also!
Great work.
I wonder: maybe all the analysis is not only inconclusive..but might also be a net negative?
Are there any F-Class shooter who just load and shoot? The hypothesis would be over analysis creates doubt and, therefore anxiety/stress..leading to poor results.
The idea being a relaxed mind and body...lead to better results?
I shoot a monthly 25 yard open sight match with .22lr
Over the years I have found the "harder" I aim...the more pre-shot thinking I do...the worse the result.
I do best when I intuitively find my aim point/hold and squeeze the trigger with little to no thought. Shooting 25 shots will take less than 3 mintues...some times faster
Thoughts?
You have a great point there. The top shooters are not doing independent science work. Instead, they spend their time on the biggest variable of all - themselves. When I was competing and not providing information, I learned to shoot what I brought to the best it would allow. I was successful in that. My hope is to allow viewers to gain valuable insights about the things they might be wasting their time and resources on.
OCW method is the key! Get the charge weight perfected and then the seating depth can be locked in. Easy peasy. :)
In my testing of seating depths, I found a strong correlation between seating depth and velocity. If you have a specific speed you are trying to reach, you can easilly get exactly there by linear interpolation of charge weight or seating depth, but a "tune" is much harder to find and even harder to prove.
Just for curiosities sake did you collect velocity data during this test? It might be interesting to see if there are any correlations there. It would also be helpful to know how much the seating depth varied by for each set. As at this point it seems reasonable to think that moving the seating depth 0.001" for each test would show smaller differences than moving it 0.010". I think it would be more helpful to first prove that seating depth makes a difference then move on from there.
I watch his videos cause I like to and xpect to pick up somthing. Q/ public assumes some things are the same as q had going in . I dont think he said he WAS looking 4 something specific.
@@roddecker1900 He was literally comparing three different seating depths to see if they generated a statistical difference within 33 shots at each depth. He didn't have a pre-determined result in mind but he was definitely testing a specific thing.
what if you want to download your bullets. So that instead of achieving 3200fps you get 2500fps? how would you get that to shoot accurate?
The only thing that is proved over and over again in my mind all these years, is that you need far more shoots to determine your theories than we thought.
Whit 3 shoot groups or 10 shoot groups you can not know...
I bet it comes down to the guy shooting the rifle over a very expansive shooting spree at one time. Shooters fatigue is real, and bet that it has more to play in this outcome than anything.
I am a hunter not a benchrest guy so I'll happily take group 1 forever.
You have an excellent point. Shooter fatigue is real, and shooter performance is a portion of the expected noise in the test.
That's very interesting information. Now, I'm wondering about all my rifles as I've picked them all based on the smallest group size. Fortunately, my main interest is about being the most efficient, effective, and precise hunter I can be.
Being that you are one of the best at explaining the technical in a way that's easily understood, do you think you can do a video on how to properly calculate a bullets BC? I often really wonder about some of the BC data provided by various manufacturers.
Interesting concept. For me, the only way I can do anything that resembles an accurate estimate is to do a comparative velocity loss over distance. That requires equipment that is a wee bit expensive. I have wondered about placing something like a Garmin unit downrange and shooting past it. I just don't know how practical that would be. Missing the mark could get really expensive.
@winninginthewind
What about the multiple speeds at distance from the Labradar? Probably not enough over a short distance, and is the accuracy at each distance completely reliable?
I'm referring to the five distances the Labradar allows between the muzzle and the 100-yard limit.
@@chrisrobinson2172 I haven't had any luck using it for that purpose.
The results suggest that there is no evidence available to us from any testing commonly carried out by shooters that would meaningfully allow us to pick any of these 3 loads as better or worse than any other, by any metric.
More questions than answers........the same result i get any time i test. Good video
Could the results be effected by moving the gun in the rest to hit the squares? The test may be verifying how the gun reacts to changing point of aim in the rest. Along with all those other variables.
There were several sources of noise in the test. That was the problem I was looking for a solution to. I wanted to come up with a test protocol that anyone could do at their local range, but I only managed to convince myself that I will have to be far more creative to design something useful.
@@winninginthewind I sure wish I had your presentation skills. You are super intelligent and look at things in a very rational way.
I've been reloading since 1957 and every time I think I know how some load/rifle combo works, something happens to prove I know nothing!? Ahh... well, the fun is in the journey. Thanks for not posing a conclusion that may or may not be statistically accurate.
For me, the question becomes 'how much is enough'? This rabbit hole goes deep! LOL~ Thanks!! EDIT: Also for me, LOW single digit SD and ES numbers are an absolute must. I'm no statistician but it seems self evident that the more consistent a load it, the more likely it would be to respond to tweeking seating depth.
How much is enough depends how good you want your answer to be. I think most statisticians would tell you not to bother with anything below 25, and 50 would be much better, if you want a pretty reasonable answer. Anything much below 25 just leaves too much chance of overlapping results, and the further beyond 25 you go the more you lessen the chance of overlapping muddying things up. Keith already mentioned that you’ll burn up barrels before finding a *really* good answer, and he’s right. That’s why he’s talking about trying to find some reasonable shortcuts without making the answers too bad to rely on. It’s not an easy feat, which may or may not even be possible.
Consistency isn't everything. Shockingly, there have been multiple tests showing the most consistent ammo performs the same or worse than the least consistent, out of a box or batch. For example, concentrisity has been fairly well demonstrated to not matter at all(in the absence of a bullet cocked 45 degrees off to the side). How many times have you seen the most beautiful groups with the ugliest chrono numbers... None of this is definitive(real science, the pre 2020 stuff, never is). Not saying make sloppy ammo, if you think something matters, test it and analyze it. If there is a statistically significant difference, it likely matters in your specific set up, no significant difference, forget about it and move on.
@@joearledge1 Good groups and ugly chrono numbers just means you’ve got it tuned fairly well. Launch a 2850 fps bullet at a higher angle than a 2875 fps bullet and they’ll go through the same hole. Launch them at the same angle and they won’t. What you’re doing when you tune your load is getting the barrel vibrations to work for you to get the required launch angle to change just enough to match the speed difference. There’s no mystery to bullets of different speeds going through the same hole. The launch angles differed.
It seems the more we dig into the established norms of load development the more we find a lot of what we've be taught is important makes no statistically significant difference in group size. Let's face it, a lot of load development was pioneered by people with borderline or actual OCD and the placebo effect is a very real phenomenon. If you believe it works, you may actually shoot better because you are more confident and more calm.
Id imagine its possible that the data could be more determinant at a farther range? Say, 600 yards? I only ask that because im finding that developing a round to group, say, 1" at 100, can be done easily, but that rounds performance at 500 yards could be the exact opposite. Basically just thinking outloud here. I will add for context the reason i ask that question is because im finding that a projectiles bc under 200 yards, for hunting, is negligible based upon caliber. I just wonder if this test was conducted at 600 or 700 yards if the data would show something different? Thank you for what you did to make this video. I really appreciate it
I may have missed it but what were the jumps in seating depth for the test? Were they all in a node, same point of impact?
Yes, Load 1 was .015" longer than Load #3, and Load #2 was between them, .009" shorter than Load #1. Somehow that sounds like a math story problem.
My Berger load for my much lesser quality rifle than an fclass rifle, would stay in reasonable tune, and when it seemed to be off, I discovered that a change in 0.007” would bring it back. I have not had to adjust my new ELDM seating length yet to see how it responds. Maybe a part 2 to this video in seating showing the difference seating can make when a person selects the zone just before and just after along with the correct or chosen seating depth. Thanks for the videos, appreciate the time and effort.
Seating depth affects pressure curve and pressure curve affects barrel harmonics. It would seem that seating depth should, by reason, affect group sizes. I think it would be far more apparent on a factory rifle than a custom build with high end components. Factory rifles are far less forgiving. I have found much greater differences created by seating depth changes in a factory rifle so that is the basis for my theory. That being said... the mystery still lives on.
My anecdotal experience is the exact opposite. I've found my factory rifles aren't all that sensitive to small changes in seating depth. I wonder if it differs from one manufacturer to another or one caliber or another. I only shoot common classics like 223 and 308, not any of the new Hornady hotrods.
@@Alan.livingston I see it in spades... my Savages (.223, 6.5CM, .308, .338LM) like short jumps - .005" to .010" and I have a Steyr .308 that likes .020" as well as a Browning in 6.5CM that likes .020" as well. The Mannlicher Schonauer in 30.06 has a long throat and is not particular. I have tested them for the most part from .005" out to .100" and each has its little sweet spot. I do see quite a bit of difference in groups through the spectrum though.
30-shot groups have a variability of 7-10%, so I believe that there is likely no difference in the three loads tested.
I have seen similar results to yours in my own tests
A serious question from a beginning precision shooter. “The first shot” or cold bore shot. Is the difference the heat of the barrel or a harmonic resonance? If its harmonics, has anyone tried to create that same resonance artificially in the barrel prior to the first cold bore shot? Or, heat the barrel prior to the first shot?
What people call cold bore is normally actually a few different things. MOSTLY it comes from clean bore. What I mean is that there are still some solvent residues inside the barrel which are cleared out with the the first shot. Also a completely clean barrel has a different friction profile than a fouled one. Most of the time you will even see this on a chronograph and the shot will be slower. Now if the barrel hasn't been cleaned this effect is typically lessened. However, when you take your gun from a warm dry house and bring it out to a wet humid day condensation will form inside the barrel. The first shot once again has to clear this out. The amount of heat transferred into the system after a single shot is very low because of how much steel there is to soak it up. So temp itself is likely one the lowest of the factors. So generally a "cold bore" shot is generated by internal barrel conditions. The "harmonics" of the barrel isn't changing between the first and second shot.
@@MMBRM Thank you for the explanation. The class I went to by a former sniper mentioned that he never cleaned his barrel but I should have asked why. Thanks again.
@@SCBCo1 You will get more consistent results in extreme precision/accuracy by cleaning the barrel to bare metal every time you shoot it and taking 2 fouling shots before you start. Simply stated you can be consistently clean but you can't be consistently dirty. However, if the situation requires consistent first round impacts with no option for sighters/foulers then you may be better off cleaning less often. However, you will reach a point where the fouling negatively affects accuracy because it changes barrel dimensions and the copper deposited on the lands can shear more copper off the next bullets. You can usually lessen barrel fouling for its life if you clean very well and make sure to remove all the copper with a bore paste for the first 50-100 rounds. You'll need a bore scope to verify it's gone.
Seems like you have to shoot this indoors, with a fixed mount and maybe look at barrel temp effects at the same time.
That is the conclusion I came to. Outdoors, even with flags results in too much confounding variance. The downside is that there isn't a rifle capable indoor range within 1000 miles of here.
"does pressure change bullet velocity" = duh. it all comes down to tuning your load to you barrel harmonics for consistency in as many areas as possible
I still think your personal biases are clouding your judgment. This video just proved to me that seating depth really doesn't matter that much. It certainly can make some difference with large changes but I think those .005 changes really don't make much difference
What method are you using to decide if they are significantly different? There are some arguments to be made that a T-TEST may not be valid because since group size should follow a random normal distribution that SD shouldn't be weighted in deciding whether or not they are from the same population(as the T-TEST does). A T-TEST would say that two sets of 5 x 5 shot groups that happened to have a smaller SD(size) when compared to another 5 x 5 with the exact same average size but which had a higher SD that the lower SD groups were statistically more different than the higher SD groups but that SD difference is just due to the random group size range of a normal distribution. Since we can only expect to predict the size range of the next group not the exact size itself.
Mostly ditto
Interesting. I've always wondered if you can legitimately do "pure science" with a human being pulling the trigger. Trigger input seems like a pretty big variable to exclude for.
How do you know you're doing Real Science?
When you end up with more Questions than Answers!
Full Factorial DOE... that is a lot of shooting.
I would like to see this test repeated at 600 yards.
Thanks fer sharing, you are an innovator fer sure, unlike the johnny-come-lately-looneytooner dude who is merely a follower & calls people stupid for past innovations.Thanks for your generosity to those whom are less innovative.