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Primer pocket uniformity?

Started by gman47564, January 02, 2022, 01:50:02 AM

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gman47564

My first question is do you uniform primer pockets ?

I been watching alot of videos on this subject.. some say its a must and some say not so much.. what are you guys finding on this matter?

My next question is about primer seating depth.. how critical is it?  If one primer is .005 below flush will it shoot differently than one seated .008 below flush.. some say it will.. some say not so much..

I know to really answer these questions is to try it for myself.. and i will. But i would appreciate you guy's thoughts on the matter.. thanks..
Grant

Rob01

I run a primer pocket uniformer on a drill through the pocket every time I prep brass but more so for the cleaning of residue than for uniforming as after the first time it doesn't seem to change much.

Never measured primer depth. A rabbit hole I won't hop into.

HufD63

January 02, 2022, 03:04:05 AM #2 Last Edit: January 02, 2022, 03:06:00 AM by HufD63
It depends on the brass IMO

If you are uniforming pockets to get uniform seating depth the critical dimensions are extractor rim thickness pocket depth and primer cup and anvil thickness. The extractor rim is what the priming tool "works" off, the rim. So if a person were trying to develop a process to achieve a consistent below flush measurement the rim is hurdle #1

Primers all have varying amounts of anvil protruding from the cup. The goal is to touch bottom of the pocket and put a uniform crush on the anvil. Measuring below flush would be a very inconsistent way to achieve this. Because of varying pocket depth, varying rim thickness and varying anvil protrusion measuring below flush would accomplish nothing in the way of uniform seating.

The only way below flush is a meaningful measurement is if you measure pocket depth and measure the primer including protrusion then do the math to see how much below flush gets the desired crush. In other words measuring every pocket, every primer and checking the below flush. There are inconsistencies in cup and and anvil in lot to lot as well as within lots.

.002" crush seem to be the minimum crush to insure good consistent ignition. This should be very similar to seating the primer until it firmly bottoms out in the pocket by feel. This explains why many of us have shot very well using any number of tools.

Getting to the point where a ladder test with primers seated .002 crush, .003 crush, .004 crush etc to find the optimum crush is a quantum leap from bottoming the primer out and calling it good.

With all that being said it's ironic you posted this because it's something I feel has been the "uncontrolled variable" in my reloading and I'm gearing up to get to the point where I can ladder what crush is optimal and be able to reliably repeat it.

As @Rob01 said it is a rabbit hole and a deep dark one at that LOL

Dave

gman47564

Thanks for that write up dave.. well said. And i agree with everything you had to say..

Heres a video i found on it.. i like this guy.. he has alot of good videos on you tube called winning in the wind..

It may or may not shed some light on this subject..

https://youtu.be/Ep4KOhCWsV0
Grant

HufD63

I like that he staggered his crush, I think .001" would be hard to accomplish and .002" should show a difference.

His results however were impossible for me "The viewer" to see.  Unless I missed it there was no mention of distance. The groups should have been shot on paper with either colored colored bullets or at seperate aiming points. I realize you could pull the individual shots off the shot marker but i would rather have a piece of paper i could look at and instantly see how they printed.

The groups or how they printed were quickly dismissed and he went straight to chrono info and I've never seen an award for ES or SD at any match I've shot. They've all been scored by group size and where they landed on the paper LOL

I completely understand the thought process and don't need any light shed on that,  I also don't believe the crush amount is a one size fits every situation but needs tested to a specific gun.

What I'm really interested in is how different people measure, sort, prime etc to arrive an exact repeatable crush. This guy skipped all that and for all I know he may have been seating to below flush with no regard for primer thickness and anvil protrusion making his test unmeaningful in regards to his goal. Probably not but you and I will have to just take his word for it that he actually got the crush he claimed.
Dave

Rob01

And a real accuracy shooter weighs each primer separately to make sure there is the exact same amount of priming compound in each. Lol

jvw2008

To me, this reloading subject is like the cherry on top of the sundae. It's the last step in making the best final product you can.

There is a lot of time and effort that goes into uniforming pockets and sorting primers by weight and/or height. More effort, is then expended getting the same amount of crush on each seated primer. I've been looking at this for about two years and have come to some conclusions that work for me.

It is too much work and there isn't enough benefit for me to chase this rabbit for plinking or steel shooting, even out to 1000 yards.

If you are going to strive for consistent pocket depth and crush, it's a lot easier if you use a high quality brass to start with. Pocket depth in Hornady brass is all over the place. In Alpha brass, it is extremely consistent. I just proved this to myself last night with 400 virgin Alpha cases, using a new tool from Primal Rights.

I have not yet done a controlled primer seating ladder with either my Dasher or BRA competitive rounds. However, random testing last year convinced me that long distance group size is affected by both primer depth and the consistency of primer crush.

The video that Grant referenced is interesting, but it's important to realize that there is not an optimum seating depth for every primer, case, and reload formula. Every rifle and every cartridge reload formula is different. I shoot two different 6mm cartridges in two different rifles. However, the primer, cup depth, powder, bullet, and bullet seating depth are the same in each of those two rifles.  One likes a 5 thousandths primer seating depth and the other prefers 3 thousandths. So just like bullet seating, there is a benefit to tuning your load via the amount of primer crush you use. If I had to guess, I would say there is a potential of improving group size by approximately 10% with this method.  To me, the effort is worth it for competitive BR shooting, but little else.

HufD63

Quote from: Rob01 on January 02, 2022, 03:47:20 AMAnd a real accuracy shooter weighs each primer separately to make sure there is the exact same amount of priming compound in each. Lol

I've been weighing them over 2 years now. I'm looking for the low end and the high end not neccessarily the exact same weight. I had a round that sounded and felt weak and hit low on the forward pit berm not making the target out at DC a couple years ago. Had to be powder or primer and since I was weighing powder on the A & D I had to believe it was a primer.
DQ'd for the match after about $900 spent in travel and hotels alone. I haven't DQ'd from a weak round since LOL
Dave

gman47564

Thank you jerry.. well said as well.. i was thinking of getting a 21'st century primer pocket uniformer but after checking the depth on 20 lapua cases and found only a .0015 difference in them.. i think i will hold off getting one.. no desire to weigh primers and probably cant seat them any better than what the pockets are.. will stick to feeling them bottom out in the cup and calling it good.. thanks for all you guys insight on this..
Grant

Rob01

Quote from: HufD63 on January 02, 2022, 04:23:23 AMI've been weighing them over 2 years now. I'm looking for the low end and the high end not neccessarily the exact same weight. I had a round that sounded and felt weak and hit low on the forward pit berm not making the target out at DC a couple years ago. Had to be powder or primer and since I was weighing powder on the A & D I had to believe it was a primer.
DQ'd for the match after about $900 spent in travel and hotels alone. I haven't DQ'd from a weak round since LOL

Was a joke but see the crew in here now so going to bow out. Never had a low power round ever so must just be lucky with my primers. You guys have fun weighing and measuring. ????

jvw2008

Dave, you and I were posting at the same time so I didn't see your question regarding techniques to assure reliable results.

As you know, Greg Dykstra (Primal Rights) believes there are typically primer seating nodes, just as we see with bullet seating depth or a narrow range of powder charge. So hitting the mark in crush to the exact thousandth may not be necessary.

I think the real key is using a tool that measures pocket and primer depth very accurately and very rapidly. The old caliper method just doesn't get it done. There are some new tools which have come out over the last few years that do that job nicely. I can tell you I am extremely pleased with the new PR tool.

If anyone is interested in this PR tool, you will have to call to order it. It's not listed on the website yet.

HufD63

Quote from: Rob01 on January 02, 2022, 04:30:52 AMWas a joke but see the crew in here now so going to bow out. Never had a low power round ever so must just be lucky with my primers. You guys have fun weighing and measuring. ????

I've had only that one low power round and after weighing 6000+ primers over the last couple years I've not found one I was scared to shoot in a match. However like i said with the money invested in getting to a match from where I'm at im not going to leave it to chance.
There is no fun in weighing and measuring primers but to know i dont have an outlier in the box is worth it to me.
Dave

LeadHammer

I have often wondered about primer depth. Maybe next time I will group like depths together, and take note. The problem I have is we get lots of wind, may not be able to see the difference with my setup.

bikemutt

If the primer seating depth is more about the distance from the primer to the flash hole rather than from the case base to the primer, I wonder if single-use, or reusable shim washers would eliminate the need to measure depth, or use sophisticated primer seating tools.

Don't you just love harebrained ideas, lol :)
Chris

jvw2008

Yo lost me with the washers Chris! ????

Can you explain more?