Question on Primer Pockets

[caveshooter]

What is the prevailing wisdom on uniforming Lapua primer pockets.

I am finding that it is difficult to fully seat CCI450 and Rem7.5 primers

in Lapua 6BR brass. So much so that I now prim on the press and have abandoned

my priming hand tool. I do clean the pockets prior to priming.

Any recommendations on a uniforming tool?

 

[gotcha]

Cup dimension for the 7.5's is .110" (depth) .......... Federal 205M is .1075". The 205m's might solve your problem. If that doesn't work call K&M and they will custom set the proper depth of cut of their primer pocket reamer/uniformer for your Lapua BR brass. I had the same problem with 6BR Norma brass and the K&M tool solved the problem without breaking the bank. The tool will also clean dirty primer pockets nicely once you've cut them to proper depth. I should add that perhaps your primers are out of spec ( too thick) Try another lot# or a different primer 1st. ........ "google": "rifle primer chart" to verify depth's of several American SR primers. Good luck!!

 

[Willie]

+1 on k&m tool. I went to it several years back, got the tool with dial indicator. You can measure cup depth on each primer, but that's a PITA, just check a few from each lot.

The k&m has a broader flat, behind the cutter, it helps cut the pocket straight. If you use a low speed drill, NEVER turn it on until the cutter is in contact with bottom of pocket. I believe the trouble people have had with uniforming primer pockets, in the past, is having the cutter take bites out of side of pocket, when using drill or case prep center that is turning, when it enters pocket. I once watched a guy using a prep center, destroy headstamp and pockets on some nice Lapua brass, doing this.

 

[Zero333]

So the problem is the diameter of the pockets is on the small side, requiring more force to fully seat them ?

Or do you think it's simply the depth of the pockets that is the problem ?

I use a Lyman Primer pocket uniformer, but not the one that you get with the handle that has a adjustable set screw, but the one that comes in the Lyman Case Care Kit and it's depth is fixed... I chuck it into a cordless and let it rip.

I find most new brass has very tight primer pockets and it takes one or 2 firings (depending on the strength of the load) to loosen the pockets to a more normal diameter / seating force feel.

After the first firing of new brass, I uniform it with the primer pocket uniformer / cutter. As a bonus, it cleans the dirt out of the pockets.

 

[gotcha]

Or do you think it's simply the depth of the pockets that is the problem ?

That's been my problem with Norma 6mmBR brass. The primer pocket depth for Norma or Lapua brass is European (CIP) standard which is a thou or two different from SAAMI spec. Caveshooter can have K&M set the cutting depth for the CIP standard. Or he can try Win SR, CCI 400, BR-4, Rem. 6&1/2 all have .109" cup depth and may well solve his problem. Frankly I've never heard of Lapua having shallow pockets. But certainly there's an exception to every rule. If a swap to the above mentioned primers doesn't work then a primer pocket uniformer/reamer would do the trick. The Rem. 7&1/2 Caveshooter is using is too tall and magnum to boot. Totally unnecessary in the short powder column of the BR case. Or with the faster burning powders normally used with it. JMHO

 

[lpreddick]

I love tight primer pockets as I tend to load to the max. I am working up loads for a modified 222 Rem to push 52 gr bullets to 3500+ fps. I hunt varmints and always fight the wind. These Lapua 222 brass have the tightest primer pockets i'v ever encountered. I could not get primers to seat completely and trying to uniform the pockets with my hand uniformer was impossible, so I mounted the uniformer in my drill and put a small drop of oil in the pocket and was able to remove enough brass that primers seat nicely and ignition has been consistent. This brass is excellent! I'm getting 3600+ fps with 50 gr bullets and pockets are still tight after 4 firings.

 

[JohnKielly]

Hang on.

Caveshooter is saying his hand tool can't seat the primers deep enough, so he has to do it on a press. That suggests to me that his hand tool is worn or suffering lack of grunt to do the job, rather than it being an issue with the case itself. He seems not to be able to exert enough leverage with it,

I regularly seat CCI 450, Remington 7½ & CCI BR4 primers in my Lapua .308 Palma cases & Lapua 6BR cases without issue using my Sinclair hand priming tool. The Sinclair has adequate leverage and minimum slop in the linkages & gets the job done.

 

[CoverDog]

Sinclair has 3 primer pocket reamers. One for LR, one for SR and one for SR Lapua Brass which cuts just a little deeper.

 

[Martin52]

What is the prevailing wisdom on uniforming Lapua primer pockets.

Any recommendations on a uniforming tool?

Yes, the PMA tool: http://www.pmatool.com/pma-lapua-sm...uniformer-complete-w-handle-and-power-adapter

I did quite a lot of research to land on this one, IMO it is the best. It cuts slightly deeper when compared to the K&M (which is fine for standard SR pockets).

 

[gotcha]

Hang on.

Caveshooter is saying his hand tool can't seat the primers deep enough, so he has to do it on a press. That suggests to me that his hand tool is worn or suffering lack of grunt to do the job, rather than it being an issue with the case itself. He seems not to be able to exert enough leverage with it,

I regularly seat CCI 450, Remington 7½ & CCI BR4 primers in my Lapua .308 Palma cases & Lapua 6BR cases without issue using my Sinclair hand priming tool. The Sinclair has adequate leverage and minimum slop in the linkages & gets the job done.

You're right John! With Lapua 6BR LEVERAGE is the key. A switch to the thin cup 205M is also a big help, for me at least. I just hate it when it takes two thumbs and a foot to seat BR-4's with my old LEE round tray priming tool. Thank goodness I bought a PMA a few years back.

 

[caveshooter]

thanks for all the great advice, I ordered the K&M tool, I am also swapping a tray of rem7.5 for fed205m with a buddy for a try, I tried measuring the primer pockets but its inconsistent with my calipers, I use the lyman hand priming tool and it takes two hands to seat primers into the lapua brass with mixed results, I than switched to the press to get extra leverage, I get to the point on the press where I feel I am using more force than should be required to seat and worry about deforming the primer and/or cracking the primer pellet