Primer pockets

[beemer]

I have a Mosin Nagant 91-30 and an M44 that I have been tinkering with using both boolits and jacketed. I noticed the primer pockets in the Grafs brass seems to be deeper than any other brass I have including another brand of the same caliber. The only way I have to measure is the tail end of a dial caliper but there seems about 10 thousands deeper than other brass.

I noticed it when I seated the CCI 200 primers. There was also a misfire with one load and a slow fire with another, it was 49.5 grs. of AA 4350 and a 150 gr. jacketed. The primer fired but didn't ignite the powder. I thought maybe the primer was seated too shallow and the primer didn't fire properly. I loaded a few more with some Fed Mag primers and they seated properly and fired fine. The CCI primers were a good bit shorter than the Fed primers. This same primer and a load of 4198 with cast does great in the M44.

I am not sure what happened, primer not seated properly, bad primer, too slow powder, need a mag primer or all the above. I don't like the primer pockets being deep, I have had this brass for a good while and haven't had any problems.

Anyone else had any problems with varying depth pockets and primer length ?

Dave

[country gent]

With the formed / swaged primer pockets there are several areas of potential problems. too deep can become a problem. .010 on a pocket .125 deep is almost 10% deeper I wouldn't see this on a military rifle as a problem since they normally have a long heavy primer strike. an uneven surface (not flat ) may not give good support to the legs of the anvil to produce good ignition. This may show as high extreme spreads or Standard Deviations. The last is a radius in the corner of the pocket that keeps primers from seating to support the legs. You can see the uneven bottom radius when you uniform primer pockets.

One other thing that could cause this is headspace issues with the brass. Could you have gotten couple cases fired several times with light cast loads where the shoulder was bumped back allowing the case deeper into chamber?

CCI primers have a harder cup than a lot of primers also. Federal one of the softer.

Thee may be several things at work here 1) the to deep pockets, 2) the primer pockets surfaces corners 3) hard primers 4) a striker spring starting to get weak 5) a striker bolt with some dirt build up slowing or restricting travel. 6) cases that are under head space.

How did the pins strike look on the one that didn't fire. normal or a light hit? On the hang fire?

[beemer]

The firing pin strike looks normal on the hang fire but the one that didn't was deeper, it did fire but must have been to weak to set off the powder. Judging from other loads fired pressure was normal. This rifle gives a strong centered hit and the pin is free, the rifle is in excellent condition with a nice bore. I have owned it probably 12 years or more with no problems.

The 7.62 X 54r is a rimmed case shouldn't give the problems of a bumped back shoulder. I measured an empty case and then seated a primer with the bolt and measured again, there was about .004 in. difference. When I got the rifle I bought 200 cases and still have some that are unfired, the pockets measure the same. They look good other than being deep but I can't tell about the corner of the pockets.

I am sort of thinking that the primers were not seated properly on these two loads causing a weak ignition.

Thanks for taking time to respond, looks like you covered most possible causes.

Dave

[country gent]

On my accuracy loads I uniform the pockets flat and make sure the corner is square. On good brass this is just a touch or so to clean up and make a completely flat surface. on some brass it may take clearing the cutter of chips once to get done. Another thing is on cases fired 10 times or more the cutter will remove a slight amount again, indicating that pressure has pushed the surface back a slight amount.

I suspect on the case that the primer fired and the powder dint ignite a problem with the powder charge or plugged flash restricted flash hole. The hang fire may have been a damged pellet in the primer, shallow seted, or aing dampness in the case or obstruction in the flash. hole

[Tackleberry41]

Only brass I have had issues w was S&B w special primers where they were not deep enough for rifle primers.

[nicholst55]

Did you measure the firing pin protrusion on your Mosins? I've never heard of S&B brass having too-deep primer pockets, just too-shallow, as Tackleberry41 alludes to.

[EDG]

Any chance you got large pistol primers loaded into your rifle ammo.

[Tackleberry41]

I bought the S&B with the idea it could be reloaded. But I am not going to spend the time fixing them. So use pistol primers with subsonic loads.

[beemer]

I had some Winchester 7.62 X 54 brass that I believe was made by S & B, I cleaned the pockets up and dedicated them to one rifle. I was using them for cast loads with LP primers anyway.

I measured the heights of several brands of primers. CCI 200 LR is .126, for comparison CCI 350 LP is .121. Win and FED LR were .130. The Rem 9 1/2 was .134.

Grafs 7.62 X 54R pockets were 1.40 deep compared to several other brands and calibers that were .128-.130. The measurements are only close, all I had was the tail end of a set of dial calipers.

I can't say for sure what caused the miss and hang fires I talked about in the first post but I an leaning toward an improperly seated primer.The firing pin protrusion is between the min. and max with the gage that came with the rifle. I think using a higher primer wouldn't hurt a thing.

Thanks
Dave