Lapua 32 Brass Issue

fc60 · Post by **fc60** » Thu Feb 06, 2014 1:07 pm

Greetings,

I recently purchased a like new Haemmerli SIG P-240 in 32 WadCutter. Firing my reloads, I was getting unexpected double shots. After trying every possible trigger adjustment I thought I had it fixed. Then, it happened again. Frustrated, I cleared the pistol and placed the unfired ammo back in the box. Then I noticed something. There was a firing pin dent on the round that chambered after the last double incident. I replaced the firing pin return spring with one that had stronger resistance and now the dent is not as pronounced.

I then took a closer look at my Lapua brass. Measuring the primer pockets, I found they were about 0.110" deep. SAAMI specs are 0.120". Thus, my primers were not seated fully and not flush.

More study revealed the following...

Commercially loaded Lapua ammo measures 0.110"-0.112". I have checked several lots.

The Lapua brass sold for reloading measures 0.120". Again, I checked several lots.

I was gifted a large quantity of Lapua 32 once fired brass in the early 1990"s and have been using it in several Walther and Haemmerli SP-20 and 280 pistols with no problems. Not until I bought the P240 did the "slam fires" begin.

As a result, I have been cutting all my Lapua brass primer pockets to the SAAMI depth for reloading.

Does anyone have knowledge of Lapua manufacturing their ammo with shallow pockets to enhance primer sensitivity?

How about our European shooters? Are Lapua primers for reloading a different dimension than the American product?

By the way, the P240 has not doubled since and has the best "squirt gun trigger" I have ever encountered.

Cheers,

Dave

ojh · Post by **ojh** » Fri Feb 07, 2014 1:16 pm

Lapua does not make primers, have no idea of what brand they use for their factory ammo.

Just grabbed a few once-fired cases of Lapua factory ammo, the pockets measured .117" - ".121".

I have reloaded Lapua brass with various makers' primers (Sellier&Bellot, CCI, Federal, Murom) and never had a slamfire in my ancient Pardini MP.

DLS · Post by **DLS** » Fri Feb 07, 2014 4:35 pm

SAMMI for small pistol primer pockets is 0.118 - 0.122

SAMMI specs also call for primers to be seated 0.002 - 0.005 below flush.

The anvil of the primer contacts the floor of the pocket before the primer cup bottoms out. This slightly crushes the priming pellet creating better ignition. The cup should bottom out as well, so that the firing pin does not have to drive the cup in deeper when firing ... if you have a weakly hitting pin ... this may divert enough energy to cause a misfire.

Primer cups have a bit of "crushability" (they will curl inward as they bottom out) before you smash them into dysfunction.

The fact that your primers were above flush needs to be corrected. You already know this. They need to be seated deeper.

While milling your pockets to within specs (this case 0.120) will never be a bad idea, I doubt the extra 0.01 inch is solving your real problem. It's not a big enough variance. I'm betting that you are not properly seating your primers in the first place.

Primers should be seated beyond the first contact with the pocket to crush the pellet, seat the cup to the bottom of the pocket and to bring the primer to at least 0.002 in below flush.

If you stop seating at the first sign of resistance you only have the anvil in contact with the pocket bottom ... you need go continue seating deeper.

I've seen lots of factory pockets that were less the SAMMI minimums, but only once was I unable to get the primers below flush without smashing them. This was with some Eastern Block mid 50's 8x57mm brass probably loaded for export to third world rebel forces ... so quality was not the most important aspect to this ammo.

Anyway ... if you are seating by feel, keep going past the first resistance,, otherwise set the priming tool to set the primers to below flush and your problems should go away.

Spencer · Post by **Spencer** » Fri Feb 07, 2014 7:22 pm

I seem to remember this 'problem' with the .32 P240 of dimpling on the primer if a shot was chambered but unfired - though doubling was never an issue with the ones that I was familiar with.
Check the firing pin spring (part #104 in the slide diagram)!

j danielsson · Post by **j danielsson** » Sat Feb 08, 2014 6:58 pm

Before I got a proper priming tool I made maybe 2000 rounds using a plier to push them in flush. Never a problem.

I once bought a wooden crate of factory lapua that said cci primers and 1.4 gr vv310 on thee red sticker on the short side. Never seen that info on other crates. I think variations may occur.

The Bear · Post by **The Bear** » Mon Feb 10, 2014 2:17 pm

Hey Dave, just wondering if you have looked at the Starline brass and how it compares with the Euro stuff?

Rover · Post by **Rover** » Mon Feb 10, 2014 4:24 pm

I'm betting you're using your press to seat your primers. Don't. Buy yourself a cheap Lee priming too and put an end to your problem.

DLS · Post by **DLS** » Mon Feb 10, 2014 5:07 pm

+1 on the Lee tool!

They are so inexpensive purchase two ... and leave one set up for small primers and the other for large. That way you save yours self the "hassle" of changing the seating rods.

Okay, I know it only takes what, about 15 seconds to change them, but hey I'm lazy, like to have spares and like any excuse to buy more tools!

Seriously though, for the money they are very difficult to beat, very easy to use, much faster than priming on the press (IMHO) and just plain work better.

fc60 · Post by **fc60** » Tue Feb 11, 2014 12:41 pm

Greetings,

The StarLine brass I have encountered is thicker in the midsection than Lapua, Fiocchi, or R-P.

If you use a full length expander for wad cutter bullets, the middle of a Starline case will bulge. Otherwise StarLine is good quality.

Cheers,

Dave