Primer Pocket Depth

[Thegreg]

Evening chaps, I've had a few issues lately with with primer/primer pocket dimensions so apologies in advance for all the questions!

Ok, so I'll start from the beginning. I primed 100 Norma .223 (once fired) cases with CCI small rifle primers, but noticed the majority of the primers sat proud of the case head by anything from .001"-.005". I chambered a few primed cases in my rifle (firing pin removed) and got a little witness mark where the bolt face closed on the primer, and the extra pressure could be felt when closing the bolt. Not happy with this so knocked all the primers out.

Looked up this page online for SAAMI primer pocket dimensions:

https://ballistictools.com/articles/...d-diameter.php

Measured the depths of my primer pockets which were all between .118"-.119", so they were in tolerance, but on the shallower end. Measured height of 100 primers and got sizes from .119"-.124". Still within tolerance but no wonder they won't sit flush in my cases, right?...

...So, I buy a primer pocket uniforming tool. This cuts the pockets out to a rather disappointing .120" deep. So with my primer pockets "uniformed" the primers still have no chance of sitting below flush.

So I'm left thinking:

1. the primer pocket uniformer should surely be cutting deeper, towards the top end of the limit (.123")?
2. CCI are inconsistent and cr@p and I need to look for a new brand of primer that are shorter?

Here's the bit that makes no sense to me: The max tolerance for the primer pocket depth is .123" but the max primer height is .126"?? Who the hell came up with those tolerances?!? So even with the pocket cut to full depth a primer at max height tolerance is impossible to sit flush.

At the moment I've no chance of success with the setup I've got so don't know whether to return the primer pocket uniformer tool or try different primers which average out below .120" (hopefully these exist).

I've got a load of brand new Lapua brass and all those primer pockets measured around .119" too, so the batch of CCI primers I have wouldn't fit those either.

Thanks for taking the time to read all that, hopefully it makes sense. Any advice much appreciated!

Cheers
Greg

[zx10mike]

if your primer uniforming tool can not be adjusted that is poor ,the k&m one can and i would recomend k&m gear highly .but i also rate cci primers.

[CROWMAN]

Hello,

I wish that I could provide the answer to your problem.

It's very strange, I have loaded many, many thousands of rounds using CCI primers, 100% for 0.223", a RCBS primer pocket tool and a very old Lee primer "loader", and I have never had a problem like yours.

Perhaps try a new pocket cleaner and another batch of CCI primers.

When you are loading the primer do you find it unduly difficult to insert the primer, pressure wise?

Good luck with solving the problem.

[Thegreg]

if your primer uniforming tool can not be adjusted that is poor ,the k&m one can and i would recomend k&m gear highly .but i also rate cci primers.

Thanks for the reply. I got the Lyman tool. It isn't adjustable but I deliberately chose a preset one. The words "adjustable" and "uniform" seemed a bit of a contradiction to me. I'm not saying it was the best choice (evidently it wasn't!) but I'll look at the K&M tool, thanks for the recommendation.

Hello,

I wish that I could provide the answer to your problem.

It's very strange, I have loaded many, many thousands of rounds using CCI primers, 100% for 0.223", a RCBS primer pocket tool and a very old Lee primer "loader", and I have never had a problem like yours.

Perhaps try a new pocket cleaner and another batch of CCI primers.

When you are loading the primer do you find it unduly difficult to insert the primer, pressure wise?

Good luck with solving the problem.

Thanks for the reply. The primers aren't difficult to seat, there's a nice amount of resistance felt when they push in and go to a solid positive stop. Perhaps the primers are a bad batch, there's a lot of variation in them and they're all on the long side. This weekend I'll get some more CCI and try another brand like Federal too.

I refuse to believe that primer pockets on brand new Lapua brass should even need to be cut, the primers should be correctly sized so they sit below flush.

Cheers
Greg

[CROWMAN]

Hello Greg,

Yes, I believe you are absolutely correct in believing that new Lapua brass should not have to be pocket cut.

It's a good sign that you have a small amount of resistance when loading the primer, that sounds good.

If it's new brass as you say, then it would seem to lead to the primers?

What primer tool are you using? LEE, RCBS ? But again as long as you are using enough pressure to insert the primer as far as it will go, then it would seem to be the primers? Again though, I have never had one instance in many many years of faulty CCI primers.

I wish I could be of more help, it's so annoying! I know from experience that these reloading problems can either intrigue you or drive you mad !

Good luck in solving the problem.

[aris]

If you are unsure of your primer pocket - one of these gauges can come in handy. I suppose you can use a calliper and measure but if you have acquired brass of an unknown provenance, this can check the pockets in fairly short order.

https://www.sinclairintl.com/reloadi...prod71030.aspx

[Randy Bohannon]

Maybe a silly question but are you seating them firmly enough?

[Thegreg]

Hello Greg,

Yes, I believe you are absolutely correct in believing that new Lapua brass should not have to be pocket cut.

It's a good sign that you have a small amount of resistance when loading the primer, that sounds good.

If it's new brass as you say, then it would seem to lead to the primers?

What primer tool are you using? LEE, RCBS ? But again as long as you are using enough pressure to insert the primer as far as it will go, then it would seem to be the primers? Again though, I have never had one instance in many many years of faulty CCI primers.

I wish I could be of more help, it's so annoying! I know from experience that these reloading problems can either intrigue you or drive you mad !

Good luck in solving the problem.

I'm using the primer attachment on my RCBS Rockchucker. I know people rate the hand held ones but you get far more leverage on the press, they are consistently seating to the bottom of the pocket, I've no doubt.

The thing that is driving me mad here is the SAAMI tolerances ALLOW this to happen! It's madness. Nothing I have is out of spec according to those tolerances, but if the primers are designed to sit below flush but the tolerance stack up allows them to sit proud then it's completely wrong IMO.

If you are unsure of your primer pocket - one of these gauges can come in handy. I suppose you can use a calliper and measure but if you have acquired brass of an unknown provenance, this can check the pockets in fairly short order.


https://www.sinclairintl.com/reloadi...prod71030.aspx

Thanks, I've fashioned a little depth gauge using a dial indicator. Calibrated it off a slip block so it's bang on.

Maybe a silly question but are you seating them firmly enough?

Yep, as mentioned above they are definitely seating down on a good positive stop.

The problem is the size of the damn things. When the physical measurements don't allow it then it's impossible to get them where they need to be.

Cheers
Greg

[aris]

Perhaps someone could stick some of their small rifle primers into a calliper and provide some measurements for comparison.

[CROWMAN]

Hello,

I have measured two primers from two different box's of CCI No. 400. Small Rifle primers.

The first one measured 0.174" diameter and a depth of 0.120"

The second one measured 0.173" diameter and a depth of 0.119"

Hope this helps?

[CROWMAN]

Hello,

Did you say that you measured new Lapua cases and the pocket depth is 0.120" max ?

Judging by my measurements, the CCi primers at my measurement of 0.120 will only just fit perfect! That is as long as you get a "full insert" into the primer pocket.

Of course if you get a batch of primers that are in excess of 0.120" , then you will have your problem of not seating flush.

Again I have never had this problem but!

Perhaps even on new brass, it might be a good idea to try a different pocket cleaner on a few cases to entirely clean the surfaces and try some primers in the cases again.

[Thegreg]

Hello,

I have measured two primers from two different box's of CCI No. 400. Small Rifle primers.

The first one measured 0.174" diameter and a depth of 0.120"

The second one measured 0.173" diameter and a depth of 0.119"

Hope this helps?

Hello,

Did you say that you measured new Lapua cases and the pocket depth is 0.120" max ?

Judging by my measurements, the CCi primers at my measurement of 0.120 will only just fit perfect! That is as long as you get a "full insert" into the primer pocket.

Of course if you get a batch of primers that are in excess of 0.120" , then you will have your problem of not seating flush.

Again I have never had this problem but!

Perhaps even on new brass, it might be a good idea to try a different pocket cleaner on a few cases to entirely clean the surfaces and try some primers in the cases again.

Thanks for doing those measurements. The CCI primers I have are mostly around the .122" mark. Some as low as .119" and a few up as high as .124". That's pretty shocking consistency.

Yes, the new Lapua brass has very consistent primer pockets, all between .119"-.120". Not much good though if most of my primers are .122"!

I ordered a K&M uniformer tool yesterday on zx10mike's recommendation. I've seen a lot of good reviews on them too so they must be pretty good. I'll see how I get on with that. I still think the primers are oversize though!

Cheers
Greg

[Black Beard]

Primer loading tools rely on the top of the rim pushing against the shell holder. Try measuring the rims or a different shell holder.

[Parabuteo]

Primers should not seat flush but slightly recessed.

Blimey, what an odd one!!

The only primer issue I had was with Wolf/Murom primers piercing round the edges. Turns out they make 2 specs of SR primer, one for .223 and one for 5.56x45, but they dont tell you that!!

[dicehorn]

I'm using the primer attachment on my RCBS Rockchucker. I know people rate the hand held ones but you get far more leverage on the press, they are consistently seating to the bottom of the pocket, I've no doubt.

I personally think the above is your problem. I have a Rockchucker but shelved the idea long ago of using the press to prime cases - you don't need that extra leverage to seat primers - seating primers is all about 'feel' especially after a few firings when primer pockets become loose and decisions have to be made to bin the brass. If a primer is seated correctly you should be able to see with the naked eye that the primer is below the level of the head stamp - my prognosis is that your press is not seating the primer deep enough.

For your benefit, I took a CCI small rifle primer (CCI 400) and measured its depth with my Mitutoya gauge and it was .121" I then took my RCBS priming tool and seated that primer into a brand new 223 Lapua case, then with a universal deprimer carefully removed the primer and remeasured its depth - now .1165". Seating the primer correctly has the effect of expanding the primer outwards to ensure a good seal in the primer pocket. Perhaps you should try that with your press method.

Maybe you have some one in your area that reloads and uses a handheld primer tool that you can use.