primer holes

rollnblock

has anyone done or read about makeing primer holes bigger? as in drilling the hole out a couple thousands bigger. pressures i would think would change. anyone ever study this as in like .005 increments?

mrbruce

I never did any studies about it, but I do know that a larger primer flash hole is detrimental to good accuracy.
I did open them up on a 6br one time only to notice the accuracy did indeed drop off a bit.

Ray B

I don't know who did the studies, but at least one of the components company had some results a few years back regarding the amount of opening between the primer and powder. In general, as the size of hole increased, the rate at which the powder was ignited was increased, and resulted in a faster burn rate for the powder, which increased the peak pressure. One study involved drilling out Berdan brass, resulting in a standard size primer hole, plus the two already there. In such cases, the powder needed to be decreased and reworked.

rollnblock

that was my thinking. a bigger flame front to ignite more powder faster would equal higher pressures.

Pinhead

The only flasholes I ever drilled larger were for shooting wax bullets and primer only loads indoors. I do deburr my flasholes though.

Studebaker Hawk

Other than duburring flash holes and uniforming primer pockets, I'd scrap them if their questionable. I collect scrap brass, and when I reach the 50lb mark it goes to the recycler. This has paid for many a primer.