Large Pistol Primer Pocket Diameter of New Brass

[RobS]

I don't have any new brass to measure so I'm asking you all to help me out by measuring the primer pockets of some of your new brass.

Thanks,

Rob

[runfiverun]

calipers and new starline 45 colt brass.
#1 .209-w x.120 d
#2 .209w x.120 d
pretty consistent i'd say

[RobS]

runfiverun:

Thanks for your measurements. Anyone else???

[lylejb]

20 year old, but still new, never primed REM 44 mag. measured with cheepo digital calipers.

.208 x .118, tried 2 pieces both same

[Mal Paso]

.208 x .120 July 2010 Starline - Genuine Harbor Freight Calipers

[JIMinPHX]

When I make press fit sleeves to convert Berdan brass to take a boxer primer, I use a .2090" reamer to size the hole. I get a normal press fit from that.

About 15 years ago, when I used to work in a machine shop with a full scale inspection department, I bore mic'd a bunch of primer pockets on new brass. They were all within about 50 millionths of each other. I don't remember the actual dimension.

In my experience, If the hole is .2085-.2095" you are OK. Large primers usually mic right around .210". The size tolerance on primers is held pretty close.

[RobS]

The dimension on the primers is what I have noted as well. I'm in the process of working the small pockets on 454 casull brass and have posted this thread for comparison of brass.

If interested here is the 454 casull LP primer thread:


http://castboolits.gunloads.com/showthread.php?t=92064

[JIMinPHX]

I just looked at that post. If I were you, I would just stay with the small primers. They are not that bad.

If you insist on trying to drill them out, the drill bit size that you are looking for is a #4, which is .209" diameter. I would expect poor results. Drill bits often make a hole that is a little bigger than they are, especially if you are using a flat point.

To do a proper job of enlarging the primer pockets, I would probably use a lathe & a small boring bar. It's an easy job to mess up though, & it gets a little tedious after you have done 6 or 8 of them.

Good luck with that though. Sometimes determination can triumph over bad odds.

Edit:
On second thought, drilling slightly undersized, then swaging with a press die is probably the best way to do that.