How Deep Should Primers Be Seated? Different Depths For Different Primers?

[amlevin]

I believe all of the manufacturers recommend seating until the anvils touch the bottom of the pocket. Seating so many thousandths from the head surface is non-sense.

Once I grasped this concept ALL of my fail to fire incidents ceased.

I now a couple of different hand priming tools, Lee with the round tray, Lee with the square tray, and a Hornady hand priming tool. All allow me to feel when the cup has reached the bottom of the primer pocket.

Funny thing, I see more and more of he Competitors at my local range using the same (with an RCBS hand priming tool tossed in for good measure) and far fewer are paying any attention to how deep the primer is seated as long as the cup is fully seated without being crushed.

If one is concerned with seating depth in primer pockets that might vary in depth then how do they reconcile the fact that the cup could then be at varying distance to the flash hole? Seems to me that a fully seated cup would yield more consistency than one that is closer or farther from the flash hole.

 

[lrgoodger]

Measuring the thickness of small rifle primers I have on hand (10 of each) results in the following (from smallest to largest;

PMC mag .116 - .119
Win .118 - .120
GM205M .118 - .121
CCI 400 .119 - .121
Rem BR .123 - .126

It makes sense that if you seat from the head of the primer and seat a fixed distance from the case head that the thinnest primers (PMC/Tula)would have the most problems if they were not seated deep enough. The first strike of the firing pin would lose its energy driving the primer deeper into the pocket. The second firing pin strike would ignite it since it is now close enough to the bottom of the pocket to crush the anvil. Using a seating method that gets the anvil against the bottom of the pocket is obviously best.

I noticed years ago that Rem primers were the thickest when I could not get them to seat below flush in Winchester .243 cases.

 

[mikecr]

I can't believe all this went onward without discussion of the indicated K&M.
Also little of pocket standards, and striking of primers, including pin settings, springs and triggers.

 

[Cakes]

I'll second what Brians356 says about the old style Lee Auto Prime. Use mostly Tula's and CCI BR and 450's in Barnard, Borden, Rem 700 actions. I have a lot of high tech stuff IMO, in my loading room and I'm pretty anal about many things but for the last 30 years (I'm going to jinx myself!!) the primers have all gone boom with the very primitive Lee tool. My recent Tula stock(not Wolf, although from the same plant) is from probably 5-6 years ago. Works for me, not going to mess with it. Very low ES/SD on my competition stuff and repeatable performance at up to minus 20F on hunting loads..no problems, Make sure it bottoms out and a little extra pressure after that. I do uniform all my primer pockets for depth and squareness. If one has loose primer pockets the Tula's are just slightly larger in diameter. Good luck, Eric in DL

 

[amlevin]

Make sure it bottoms out and a little extra pressure after that.

With the Wolf/Tula primers I can actually feel the two different "contacts" as the primer is seated, using my Lee priming tools. First when the anvil hits the bottom and then when the edge of the cup hits the bottom.

With the Hornady hand primer, that uses a full hand grip rather than just a thumb, I have less feel. Use it for primers that are made with the anvil almost fully seated in the cup rather than with the extra protrusion the Wolf/Tula's have.

 

[mikecr]

I wish you could all try an indicated K&M so that you could see that you cannot 'feel' with any precision at all.
This is analogous with seating bullets by feel.
You would also see that even with pockets cut to uniform depth, the primers themselves vary a good amount in height.
Setting primers either to .xxx below the case head, or until 'bottomed' is not correct.

I also notice that success in this, here, seems measured by number of misfires. Let me tell you, it often takes incredibly bad seating, combined with bad striking, to cause actual misfires.
Not so much to cause flyers..
Don't blindly think that your powder ignition is optimum and consistent just because all the primers are going off.

Ever wonder why one primer performs better than another with your load?
It's not because one is better than another. It's because one is igniting more consistently than another -with your system(both equipment and procedure).

 

[MajorHeadTrauma]

Hi,

I have enjoyed this thread.

Regardless which brand of primers I used, I have found having a consistent primer placement important to maintain any control of SD/ES.

In has been my experience, that hand priming with a quality tool coupled with uniform primer pockets is critical.

Does this matter at 100 yards for someone that wants a 1 MOA group? Not likely. Sub MOA at 1,000 yards? Yes!

I have found this tool to be my favorite:

http://www.21stcenturyshooting.com/S.S_FQUY.php

This is not a direct endorsement, but as a suggestion to tighten up the spreads.

Thanks for allowing me to share.

 

[BoydAllen]

Take a look at the short range benchrest record book, or any group match report before you equate hand seating of primers with inferior results. At least for those distances I am calling BS on any assertion as to the inferiority of hand seating by feel. Virtually all of the benchrest competitors that I am aware of seat their primers by feel, even the one that uses a bench tool. The statement that this method is all right if you are satisfied with 1" groups is pure bull.

 

[GLC]

I read this thread with interest, I too have just experienced a similar problem with the KVB7 primers, today I have 4 maybe 5 fail to go off at our GB Long range National Championships, they all ignited on second firing,I have the 21st century adjustable priming tool, recently I had to change case holders (usually it stays as my magnum tool and I have another for the .308 case)

After using it I put it back together and realised that I had not recorded the previous depth setting so I checked on the 21st century website and it advised to turn the tool head 10 clicks which is a good average for most cases, I was concerned that it was too much however it now appears not enough, I am going to measure the depth with my standard Lee tool and the 21st century and adjust it accordingly.

My concern was seating the primers too deep however it appears it is actually reverse.

 

[BoydAllen]

I set my 21st century too so that no amount of hand pressure can force the handle to touch the tool's body while seating a primer. That way the depth and preload of the anvil into the pellet are entirely determined by my hand pressure, and feel.

 

[MajorHeadTrauma]

Take a look at the short range benchrest record book, or any group match report before you equate hand seating of primers with inferior results. At least for those distances I am calling BS on any assertion as to the inferiority of hand seating by feel. Virtually all of the benchrest competitors that I am aware of seat their primers by feel, even the one that uses a bench tool. The statement that this method is all right if you are satisfied with 1" groups is pure bull.

My apologies regarding my earlier post. It was in no way meant to misinform anyone.

I'd appreciate to speak with you directly apologize about my earlier post. I think we are like minded, but would to better explain my post.

Thank you in advance.

Kirk

714 401-5612

 

[GLC]

Thanks Boyd, very helpful.

 

[BoydAllen]

Kirk,
Enjoyed our conversation on the phone. Of course no apology is needed. Those only come into play in cases of personal attacks. This has just been a discussion.

 

[MajorHeadTrauma]

Kirk,
Enjoyed our conversation on the phone. Of course no apology is needed. Those only come into play in cases of personal attacks. This has just been a discussion.

Thanks Boyd,

You are a true gentleman and an inspiration. Thank you for your time and allowing me the opportunity to drain your brain.

To all the guys on the board, Boyd took his time with me and I learned a great deal.

Thanks,

Kirk

 

['Freak]

The text along with illustrations in a “Forster Products Catalog #82” has “ideal” as anvil feet on the floor, anvil legs slightly preloaded, and the primer cup still a bit short of touching bottom. They’re saying cup on the floor is too far and very possibly damaging. Glen Zediker says much to same in “Handloading for Competition”.