FINALLY, I HAVE SOME ANSWERS!!!

Was distracted this morning when I showed up to work, my chief engineer asked me what I was thinking so hard about, so I told him. He took me out to the machine shop and after searching high and low for about 10-15min, finally found them and handed me a pair of Starrett Small Hole Gages and a pair of Starrett Micrometers (0.0001" precision). Told me to borrow them for the night and I'd have my answer, whether it was out of spec primers or out of spec primer pockets in the brass.

So, as soon as I got home, I started measuring. What did I find? Well let me tell you!


I found the specs for primers as well as primer pockets ( http://ballistictools.com/articles/p...d-diameter.php ) and started measuring 10 each of LC LR 07 primer pockets, CCI BR2 LR primers, WLR primers, and some other misc brass.


All of this data was taken from measuring between 10-20 cases/primers, and recording the measurement 3 times, the writing down the average of those 3 for all cases/primers. The same measurements between cases were VERY consistent.

LR Primers
Min = 0.2105"
Max = 0.2130"

LR Primer Pockets
Min = 0.2085"
Max = 0.2100"

CCI BR2 Primers - 0.2111" (middle of spec)
WLR Primers - 0.2103 (lower end of spec)

LC LR 04 Primer Pockets - 0.2094" (in spec)
LC LR 07 Primer Pockets - 0.2106" (above spec)
LC LR 08 Primer Pockets - 0.2097" (in spec)
LC LR 10 Primer Pockets - 0.2100" (max spec)
LC LR 11 Primer Pockets - 0.2095" (in spec)
R-P Primer Pockets - 0.2098" (in spec)
Black Hills Primer Pockets - 0.2100" (max spec)

I STILL don't have the Lapua brass, not happy with SouthwestAmmunition for that, they were in-stock when I ordered, then they claimed they must have sold out after I ordered even though the page still hasn't changed like some other items that say "Requires an additional 1-2 weeks processing time)". Anyways, I don't have that brass in yet so I can't measure the primer pockets to see what they are.

What I think happened is that the LC LR 07 primer pockets were a few ten thousandths (as in, as much as 0.0003"-0.0005") larger than the primers, which caused less friction to hold the primer in place, so the primers were easier to unseat and blow out. When I get time, I'll be pulling the remaining 51rds, weighing charges to ensure that wasn't a contributing factor too but will then just load up the Lapua brass with a smaller range of powder charge and retest.

Oh and my Timney Trigger arrives today to fix the XMark Pro Trigger Recall problem. So that should be fun.