Major Factor in Primer Seating Depth Variability

[Bryan Z.]

I'm not a pencil pusher so I don't geek out looking at spreadsheets, some nerds get a tingle up their leg analyzing all that nonsense, paper target never lies and most of the time tells me all I want to know, I'm a meat and potatoes kinda guy and have zero interest in all this overload of statistical crap it is just a waste of time IMO of course.

Cool. I like meat, potatoes, all the fixins, and a strong mead.

 

[D Coots]

As good as Boyer shot he's probably the King of spreadsheets....

 

[Bench Addict]

Bryan Z. isn't wrong here. I discussed this issue with him about 2 weeks ago, it's a problem with almost every primer seater out there. I data logged the results from my CPS and sent them to him, which he then took and compared against his equipment. I can appreciate what Bryan is doing as I'm every bit as far down the rabbit hole as he is. Some people can appreciate the mathematics behind extensive testing and put it to good use while some others can't: gives them a headache trying to put it all together. I will be spending most of my winter working on various primer tests and getting all of the data together in an easy to read format. As for the world of primer seaters, "good enough" doesn't cut it anymore. People want full control of primer seating and this general tolerance of 0.002 - 0.003" is becoming unacceptable. We measure almost everything thing else down to 0.0005" (half thousandth) so why in the world would anything over 0.001" be acceptable for primer seating??

 

[Bench Addict]

I also wanted to add that I commend Bryan for doing this testing and putting it out there, should have been done at least a decade ago and why the manufacturers have all ignored this is beyond me. Perhaps it's because they assume most don't uniform primer pockets. Regardless of whatever reason that may be, I have dug to get answers and spoken with some of the most famed shooters on this subject and gotten very minimal feedback. I have reached out to Brian Blake about some ideas on his Autodod with a product that is in development that could solve the issue of case rim thickness variation.

 

[quest450]

It is going to be difficult to achieve uniform primer seating depth when your primer pockets aren't uniformed and depth varies from 0.120 - 0.124",
it's easy to blame the $600+ Gucci priming tool for your error, I do uniform my primer pockets and use CPS for my match ammo and 90% of my loads are dead nutz at 0.008" deep with 0.0005" tolerance, I also seat primers by feel using the Sinclair hand primer when testing loads at the range but I'm nowhere near as consistent as using CPS at my reloading bench

 

[BoydAllen]

Bryan Z. isn't wrong here. I discussed this issue with him about 2 weeks ago, it's a problem with almost every primer seater out there. I data logged the results from my CPS and sent them to him, which he then took and compared against his equipment. I can appreciate what Bryan is doing as I'm every bit as far down the rabbit hole as he is. Some people can appreciate the mathematics behind extensive testing and put it to good use while some others can't: gives them a headache trying to put it all together. I will be spending most of my winter working on various primer tests and getting all of the data together in an easy to read format. As for the world of primer seaters, "good enough" doesn't cut it anymore. People want full control of primer seating and this general tolerance of 0.002 - 0.003" is becoming unacceptable. We measure almost everything thing else down to 0.0005" (half thousandth) so why in the world would anything over 0.001" be acceptable for primer seating??

This makes my point about a lot of assuming going on. How many records do you own? Personally, I do not even approach that level, but I pay attention to those who do. One of the things that I hear a lot when I am helping guys upgrade their shooting game, in basic ways, is the old "It seems to me...". More often than not actual on the ground experience contradicts their assumptions. Often things do now work the way we would think that they would. Having the ability to measure something to a thousandth or even ten thousandth is noting new, not at all.

 

[BoydAllen]

I'm not a pencil pusher so I don't geek out looking at spreadsheets, some nerds get a tingle up their leg analyzing all that nonsense, paper target never lies and most of the time tells me all I want to know, I'm a meat and potatoes kinda guy and have zero interest in all this overload of statistical crap it is just a waste of time IMO of course.

Statistical analysis is just a tool, that like any other tool can be useful for a particular task or not, which can be used properly, or not. One does not need to get a tingle from using a hammer to be motivated to use one to drive nails rather than a rock. Insulting someone for having more tools does not make sense to me.

 

[Bench Addict]

It is going to be difficult to achieve uniform primer seating depth when your primer pockets aren't uniformed and depth varies from 0.120 - 0.124",
it's easy to blame the $600+ Gucci priming tool for your error, I do uniform my primer pockets and use CPS for my match ammo and 90% of my loads are dead nutz at 0.008" deep with 0.0005" tolerance, I also seat primers by feel using the Sinclair hand primer when testing loads at the range but I'm nowhere near as consistent as using CPS at my reloading bench

Out of my CPS: +/-0.001" is the very best I have been able to achieve using Lapua brass with pockets cut at 0.1315" depth using 21st Century pocket uniformer and using Primal Rights PrimeWhere and AccuracyOne w/ 0.0001" Mitutoyo Absolute Digimatic Indicator. My results align with Bryan's test results. Unless we are both testing w/ CPS units that have internal tolerance issues, I have to assume that people getting better results are using measuring instruments of lower accuracy/resolution or they aren't checking every single primer they seat. If someone is using of equal or greater quality indicators and getting better results than I am showing, please share your results. Attached are photos of my equipment used to cut, measure & seat primers. Primer pocket variation on this batch of 50 (LRP) is +/-0.0002". I would love nothing more than to have my seated primers measure within a +/-0.0005" tolerance. I will post my data log of the measured pockets and primers soon, once I locate them in my files.

 

[BoydAllen]

It is going to be difficult to achieve uniform primer seating depth when your primer pockets aren't uniformed and depth varies from 0.120 - 0.124",
it's easy to blame the $600+ Gucci priming tool for your error, I do uniform my primer pockets and use CPS for my match ammo and 90% of my loads are dead nutz at 0.008" deep with 0.0005" tolerance, I also seat primers by feel using the Sinclair hand primer when testing loads at the range but I'm nowhere near as consistent as using CPS at my reloading bench

Actually, uniformity of pocket depth has nothing to do with uniformity of seating depth. Seating depth is measured from the case head. If the seating punch protrudes the same amount from the tool, and the head of the case is forced against the tool, seating depth will be uniform. Compression, or bottoming may not be, but depth will.

 

[Bryan Z.]

I always appreciate when someone takes their time and resources to test and post results. I thanked him for doing so and received rudeness for my efforts.
I just choose a different path to achieve the goal but I’m out on this member.

Sorry that was your perception. And you did thank me while injecting your personal philosophy about the utility of data to inform practice. That derailed what is a good thread with robust discussion that started with a presentation of data in my video. I’m sure there is some other philosophy of science web forum out there where you can express your views about the utility of data which would be pertinent to what they are discussing. Here we are discussing the data and sharing ideas on how to compensate for this obvious point of error that affects precision. We are trying to be better shooters despite your attempts to derail the thread. Please, for our sake, go to some other website to post about your philosophy on data and refrain from derailing this one.

 

[Bryan Z.]

Actually, uniformity of pocket depth has nothing to do with uniformity of seating depth. Seating depth is measured from the case head. If the seating punch protrudes the same amount from the tool, and the head of the case is forced against the tool, seating depth will be uniform. Compression, or bottoming may not be, but depth will.

Thanks Boyd! This was going to be my exact response and I was going to mention how the data showed no correlation between pocket depth and seating depth as stated in my video.

 

[WSnyder]

Thanks Boyd! This was going to be my exact response and I was going to mention how the data showed no correlation between pocket depth and seating depth as stated in my video.

Just to clarify some details: Wouldn't you need/want a uniformed pocket depth to take advantage of a tool like the Sinclair that indexes on the base of the case to get uniform seating depth? Seems to me that uniformed pockets registered from the base would be a requirement. I understand with your test it didn't correlate but you weren't using a tool such as the Sinclair.

 

[Murray Brook]

Actually, uniformity of pocket depth has nothing to do with uniformity of seating depth. Seating depth is measured from the case head. If the seating punch protrudes the same amount from the tool, and the head of the case is forced against the tool, seating depth will be uniform. Compression, or bottoming may not be, but depth will.

I understand what you are saying about uniformity of seating depth but if you don't uniform the pocket to acheive proper crush what would be the point. Just trying to learn.
@Bryan Z. Good video

 

[Bryan Z.]

Just to clarify some details: Wouldn't you need/want a uniformed pocket depth to take advantage of a tool like the Sinclair that indexes on the base of the case to get uniform seating depth? Seems to me that uniformed pockets registered from the base would be a requirement. I understand with your test it didn't correlate but you weren't using a tool such as the Sinclair.

I’m not advocating against uniform pocket depth just that there was no correlation even with the Lee APC where there is no rim thickness effect like the Sinclair. That seems to be why the Lee primed to .008” depth with almost no variation unlike the other tools I used that were rim thickness dependent.

 

[Bench Addict]

This makes my point about a lot of assuming going on. How many records do you own? Personally, I do not even approach that level, but I pay attention to those who do. One of the things that I hear a lot when I am helping guys upgrade their shooting game, in basic ways, is the old "It seems to me...". More often than not actual on the ground experience contradicts their assumptions. Often things do now work the way we would think that they would. Having the ability to measure something to a thousandth or even ten thousandth is noting new, not at all.

This trivial here on primer seating depth variation has nothing to do with my shooting records. Unless bad shooting can lead to primer seating depth variation? Obviously not. This is strictly a reloading bench quest to find what primer seating equipment (or methods) produce the most uniform primer seating depths. If you're not interested in these tests, then don't follow the thread. Stick to whatever you've been using that works for you or go elsewhere for tips on priming from someone you trust.

 

[BoydAllen]

This trivial here on primer seating depth variation has nothing to do with my shooting records. Unless bad shooting can lead to primer seating depth variation? Obviously not. This is strictly a reloading bench quest to find what primer seating equipment (or methods) produce the most uniform primer seating depths. If you're not interested in these tests, then don't follow the thread. Stick to whatever you've been using that works for you or go elsewhere for tips on priming from someone you trust.

Yea, I was looking for direction as to what I read or how I respond. Sure I am.

I agree with your last sentence.

The reason for my interest in this thread is that there is so much talk about the importance of seating to a particular depth, and I know shooters who are better than most of those that have posted that it is, that seat by feel alone.

IMO one of the severe problems with the internet is that guys that are new to the sport, or who are looking to up their game do not have any way to distinguish good advice from bad. Over many years I have tried to report what the best shooters do, and in some cases, what has worked for me. While we are all free to use screen names, I choose not to.

 

[6Creed73]

Yea, I was looking for direction as to what I read or how I respond. Sure I am.

I agree with your last sentence.

The reason for my interest in this thread is that there is so much talk about the importance of seating to a particular depth, and I know shooters who are better than most of those that have posted that it is, that seat by feel alone.

IMO one of the severe problems with the internet is that guys that are new to the sport, or who are looking to up their game do not have any way to distinguish good advice from bad. Over many years I have tried to report what the best shooters do, and in some cases, what has worked for me. While we are all free to use screen names, I choose not to.

I'm sure there are guys who can seat by feel and get consistent seating. But seating by feel is ambiguous and can be difficult to learn unless you have a mentor to teach you that kind of stuff and what to look for.

I'm a systems engineer, and it's in my nature to prefer data and repeatable, measurable methods without relying on the human factor. Even if I knew how to seat by feel, my brain would never allow me to be confident that they are all the same. However, when I uniform the pocket, take a measurement, seat primer, take a measurement...I'm 100% confident with the result. It's peace of mind for me. That doesn't make other methods wrong, just different ways to accomplish the same thing.

With that said, people just need to do what works for them and enjoy the hobby. Reloading can be both an art and a science.

 

[Bench Addict]

I'm sure there are guys who can seat by feel and get consistent seating. But seating by feel is ambiguous and can be difficult to learn unless you have a mentor to teach you that kind of stuff and what to look for.

I'm a systems engineer, and it's in my nature to prefer data and repeatable, measurable methods without relying on the human factor. Even if I knew how to seat by feel, my brain would never allow me to be confident that they are all the same. However, when I uniform the pocket, take a measurement, seat primer, take a measurement...I'm 100% confident with the result. It's peace of mind for me. That doesn't make other methods wrong, just different ways to accomplish the same thing.

With that said, people just need to do what works for them and enjoy the hobby. Reloading can be both an art and a science.

Well said, couldn't agree with you more. It's like: I could torque lug nuts by hand and get a really good feel for it but I'd much rather use & trust a calibrated torque wrench to do the job accurately and consistently every time.

 

[stavey]

Anytime you prove a tool that costs 1/6 the price works better than the more expensive tool you’re going to ruffle some feathers. LOL

 

[memilanuk]

Leaving aside the Lee ACP results - they are what they are, and I'm disputing them - does anyone here have any good guesses why the CPS would have so much more variation than the PMA? Given that they both reference off the case rim the same way, and both appear to be pretty solidly made... it seems odd that there was such a difference. I'm not disputing or challenging Bryan's numbers, I'm just trying to make sense of *why*...