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

[Alexander-M]

<< There is another on-going thread about primer anvils, and my following specific experience is closely related. >>

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Summary -
TEST 1 Fully seated primers:
Tula KVB-7 > 1 out of 100 failed to fire on first strike, OK second strike.
Many 1000's of other brand primers never failed to fire when seated in the same manner.

TEST 2 Primer Depth Limited to 0.004 inches
Tula KVB-7 > 4 out of 20 failed to fire on first strike, OK second strike
CCI-200 > All fired fine

TEST 3 Fully seated Tula
20 out of 20 fired fine.
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A few weeks ago, I bought Tula KVB-7 primers (new to me), and used 100 of them on 2X fired Lapua brass, with the primer pockets cleaned. I used the RCBS Jr press and fully seated the primers; i.e., as far as they would go while applying reasonable force on the lever. The accuracy of the Tula primers was excellent, perhaps even just a bit better than CCI-200’s or WLR. However, one of the Tula primers failed to go off on the first strike of the firing pin, but did fine the second time.

Then I read about the potential advantage of seating primers to a precise depth, and bought Holland’s Perfect Primer Seater, which had received great reviews. I really like the ease of use of the RCBS Automatic Bench Priming Tool that Holland uses, and the concept and excellent workmanship of Holland’s added primer depth control.

However, now I wonder about the efficacy of restricting the primer depth.

I set the Perfect Primer Seater so the primers would be seated 0.004 below the case, and primed 20 rounds with CCI-200 (again, using 2X fired Lapua brass, with the primer pockets cleaned), and 20 rounds with Tula KVB-7, to evaluate them against each other.

All the rounds with the CCI-200’s fired fine, but four of the Tula’s did not go off on the first firing pin strike, yet did OK the second time. I attributed the problem with the Tula primers to insufficient seating depth based on something I read not long ago in this regard.

I loaded 20 more rounds with the Tula primers using just the RCBS primer seater without Holland’s depth limiter, and all fired OK. The seating depth of the Tula primers seated ‘fully’ without restriction varied between 0.010 and 0.012 inches - quite deeper than the previously limited depth of 0.004 inches.

Now the burning question is, “How deep should the primers be seated?”
Should the Tula’s be seated as far as they will go?

I seated CCI-200 and WLR primers into brand new Lapua brass with just the RCBS seater so they would be ‘fully seated’, and their depths varied between 0.005 and 0.009 inches, with most being 0.006 inches. (Haven't fired them yet, but strongly suspect they will be fine.)

Is there a risk of 'no-fires' by restricting the seating of the primers to a depth that keeps them from being fully seated and perhaps keeping the anvils from being properly compressed?

Your opinions will be most appreciated!

Nando

 

[BoydAllen]

All of the short range benchrest shooters that I know of seat by feel. My version of that is to feel them bottom, and then apply a moderate amount of preload. I have not shot many Russian primers, but the ones that I did all went off the first time. It is my understanding that the pellets in Russian primers are of a completely different composition than others, that they are more like plastic. Back in the day, when I was working with my hands a lot, and had a pretty firm grip, I must have been overdoing it a bit, because I ruined a RCBS hand priming tool distorting the lips that retained the shell holder. All of the primers went off, and there was no evidence of any problem.

 

[jimcasey01]

Nando,
I have used Wolf (Tula) small rifle mag primers for 5.56 for a few years in .223 with no problems, as a matter of fact they performed better than any other of the many primers I tested. When I started seating the same primers on a newly acquired press (I love the press otherwise), I had so many fail to fires, I was shocked and embarrassed. I returned to hand priming the same brass with the same primers, and have had no fail to fire in a few thousand rounds fired since. As Boyd stated, with hand priming, you can truly feel the primer seat, then give a bit more to set the anvil and life is easy. Fail to fires become a true rarity.
Good luck,
Jim

PS In defense of the press, I had uniformed the depth of the primer pockets about .0015-.002 deeper than normal so that all primers seated to the same depth.

 

[22BRGUY]

Might just be me, but I found with Lapua brass, that if I uniformed the primer pockets, I had misfires with Wolf primers. The only theory I have is that the primer pockets got cut deep enough by uniforming, that the firing pin could not extend far enough out and was not able to strike them deep enough to ignite. Non uniformed pockets had zero issues.

 

[jimcasey01]

Might just be me, but I found with Lapua brass, that if I uniformed the primer pockets, I had misfires with Wolf primers. The only theory I have is that the primer pockets got cut deep enough by uniforming, that the firing pin could not extend far enough out and was not able to strike them deep enough to ignite. Non uniformed pockets had zero issues.

Are you certain that your primers are fully seated? I am using Lapua brass with Wolf SRM primers, and as stated above, zero fail to fire when properly seated. When not fully seated, a lot of fail to fire.

 

[Trevor60]

Evening

I have the Tula SRM primers, with a bench mounted priming station with incremental adjustments. I have used the same system for years and the WLR, Federal, and Remington have had zero FTF. With the Tula primers i have just over 1% failer rate. I have adjusted the depth of the primer from flush to slight (visible) crush with similar results. i can not get 100% ignition from this lot of Tula primers.

F/TR Bolt action rifle: I thought it was the firing pin so i measure the protrusion at .0375. This number is low for a custom action so i order a new firing pin and the new length was .0475 with the new firing pin i expected 100% ignition... sorry again i had FTF but not with the Fed or Rem i am not sure if the cup is too hard or other factors. When breaking down the FTF loads i have only seen one primer with no anvil. i can provide the lot number put i bought these primers in 2012 so i am not sure if this is relevant to the ops issues.

If anyone has a solution i am open to suggestions i am sitting on thousands of these primers.

Trevor

 

[BoydAllen]

What action?

 

[R.Morehouse]

I seat mine 3K deep. I use the Perfect Primer Seater from Holland Guns. It comes with a gage to double check, I check every one and they all go bang.....I use CCI and Fed. primers...

 

[Webster]

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. The primer pockets are swagged into the case head not machined to a precise dimension. The only reason people get away with it is because the primer cup is firmly gripped and energy isn't lost pushing the cup forward. Apparently the firing pin has enough force to smash the cup into an unseated anvil with enough force to set it off most of the time. Cups are made to different thicknesses they are not all the same. If the anvil legs are touching the bottom of the pocket no energy is lost pushing the cup or anvil forward. Anyhow this is my take on it after reading many articles.

 

[rox]

I've loaded about 3500 KVB-7 in the last few months. The primers are seated firmly against the bottom of the primer pocket. There has been one failure out of 2800 fired so far, and the strike was clearly light.

One thing was clear from the start: My Dillon primer tubes would only hold about 96 GM210M primers, but they swallow 100 KVB-7s. Maybe the KVB-7s are shallower (and therefore seat deeper in the primer pocket), or perhaps the cup is just more rounded so they mesh together more closely when stacked in the tubes.

 

[Alexander-M]

I seat mine 3K deep. I use the Perfect Primer Seater from Holland Guns. It comes with a gage to double check, I check every one and they all go bang.....I use CCI and Fed. primers...

Yes, and my problems with the Tula KVB-7's started when I began using Holland's Perfect Primer Seater set to 4K.

No issues with other brands, or very little with the KVB-7's seated without depth restriction.

As several contributors have pointed out, seating the primer fully is likely the best approach. I can definitely feel the primer being seated with the RCBS Automatic Bench Top priming tool, and will continue to use it henceforth.

I also have had good experience with the Tula KVB7's accuracy-wise, and have a primer usage guideline that works for me based on number of times the brass has been fired, and measuring the diameter of the primer pockets.

Provided different circumstances and case preparation other than what I do, I suspect that there may be a good application for Holland's Perfect Primer Seater to seat the primers to a specific depth. But for now, I will just do it by feel, as I had done for too many years.

Thanks for your inputs!

Nando

 

[22BRGUY]

Might just be me, but I found with Lapua brass, that if I uniformed the primer pockets, I had misfires with Wolf primers. The only theory I have is that the primer pockets got cut deep enough by uniforming, that the firing pin could not extend far enough out and was not able to strike them deep enough to ignite. Non uniformed pockets had zero issues.

Are you certain that your primers are fully seated? I am using Lapua brass with Wolf SRM primers, and as stated above, zero fail to fire when properly seated. When not fully seated, a lot of fail to fire.

I was am sure they were both full seated as I was using a K&M hand priming tool which is good for feeling the bottoming out of the primer and then adding just a slight amount more pressure, but thanks for good question.

 

[BoydAllen]

Nando,
Rereading your earlier post, you mentioned that your used your RCBS press to seat primers. Was that with the original primer arm that came with the press? If it was, I may have some information that would interest you.

Decades ago, I did a test. I had read an article that said that the usual press setup for seating primers was not good because the press had too much leverage and that a hand seater was better because it gave better feel, and would not be as prone to overdoing seating pressure.

At that point I had been using a hand tool, but I had the setup that came with the press.

Being the curious sort (still am) I decided to try the press setup and seated some primers with it, then out of curiosity I took one of those primed cases and applied my usual pressure with my hand tool, and was surprised to feel the primer seat deeper into the pocket.

At first I could not understand why this was until I realized that with the press setup I was priming at the bottom of the ram's stroke, where the press had its least mechanical advantage.

It turned out that like a lot of people about a lot of things the author had guessed and assumed when he made his statement about press priming....and was very wrong.

Some time later I purchased an on the press priming attachment by RCBS that screws in to the top of the press like a die, and found that by fine adjustment of its height in the press threads that I could cover quite a range of different mechanical advantages, and choose the one that gave me the best feel when primers first bottomed and for preload.

I still use a hand tool for most of my primer seating simply because I do most of my loading at the range and I dislike removing my FL die from the press every time that I want to prime, but that press top setup is still a very good alternative as far as feel goes.

Here is the priming arm that I used for my test, all those years ago,
http://www.natchezss.com/rcbs-universal-priming-arm-2.html
and here is the press top tool.
http://shop.rcbs.com/Products/Priming/Tools/Ram-Priming-Unit.aspx


The latter is not expensive, and you might find that it was interesting to work with for your Russian primers. Just do some experimenting with the height of the part that threads into the press like a die, to find the sweet spot.

 

[PMA3]

Has anyone tested the new ADJUSTABLE Bald Eagle Primer Press sold by bullets.com?

 

[Alexander-M]

BoydAllen wrote, in part:

Nando,
Rereading your earlier post, you mentioned that your used your RCBS press to seat primers. Was that with the original primer arm that came with the press? If it was, I may have some information that would interest you.

Yes, the original. But now I use the RCBS Automatic Bench Priming Tool, and I believe that besides having better leverage, it does allow me to feel the priming operation better. I imagine that a hand-held primer provides better feel. I like the ease of use of the RCBS Automatic Bench Priming Tool, though.

That is good information you shared with us, and certainly worth considering.

Thx!

Alex

 

[BoydAllen]

Having looked over a preliminary report on the Bald Eagle tool, it looks to me like the adjustment feature works the same as the 21st Century stainless hand tool that I have. I like the feature. On the hand tool, the adjustment varies the height of the case in relation to the maximum extension of the seating punch, which allows the user to end his seating stroke with the handle in his preferred position, and make sure that it does not bottom on the body which would limit how primers were seated. I can see where some would prefer a bench tool for preloading relatively large lots of ammunition. The workmanship and design of the Bald Eagle tool appear to be first rate, but I have not handled one. Shiraz (Bald Eagle's owner) is an accomplished competition shooter (F class) and brings that experience to the task of product design and selection, to the advantage of all of us who continue to look for better products.

 

[Brians356]

FWIW I have reloaded for twenty years, over 2000 rounds, always using a Lee AutoPrime hand tool. I've never had a misfire with 7-1/2, BR-4, WLR or WSR primers. I uniform all primer pockets using the Sinclair tool, and seat until I feel the anvil bottom out, then give it a little more preload. I always check visually and by feel, but this method always leaves the primer recessed below the case base "a few thousandths".

 

[Lapua40X]

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.

What he said ..................

 

[JohnKielly]

It got to the stage that arthritis stopped me seating primers one handed with my Sinclair priming tool and I couldn't feel them in any more with two thumbs doing the seating so I bought a K & M dial gauge seater ( https://www.kmshooting.com/catalog/primer-seater-tools/primer_gauge.html ). It's so much slower to operate as you go through three steps:

• Measure each primer from anvil feet to face of cup relative to the depth of each case's primer pocket
  Swap the primer into the ram & replace the case
  Seat the primer with .003" crush for LR primers & .002" for SR primers.
  

What it does do beside give me the best velocity spread figures for years is show just how much more effort is needed to seat Russian primers correctly than most of the standard ones.

 

[hogan]

Primer MUST be seated Flush so as to have no protrusion, otherwise could have an out of battery discharge if primer is higher than case rim.

Better to seat at least .005" below flush to rim.

Better still to uniform your primer pockets and seat primers fully using unified depth so get consistent ignition.


There are defective primers out there. Got a bad 1k from CCI about 10yrs ago. Loading small rifle primers in Starline .454Casull brass, unfired. Ruger Super Redhawk would not ignite about 60% of the loads. Starline brass has Very Uniform primer pocket depth. Ascertained with Starrett depth Micrometer. CCI tried weasling out on their product saying was bad brass and firing pin strike was "seating the primer". BS...

CCI finally told me they would pick up and replace the primers. SOB lied to me; they never did...

I never bought another CCI primer....


Always seat primer as deep as can in case.
Do not vary seating depth by brand. The brand will have its own dimension.

I advise keeping track of primer lot #s. If run into a bad lot, you won't have to pull 400rds of hard crimped magnum loads like I once did, not being sure which rounds were loaded with which lot of primer... Last thing you want on a defense handgun is to doubt your primer will fire....