Home Forums Hunting & Shooting Gunsmithing Cerrosafe tips?

Just a couple of random thoughts...if it's phenominally accurate, why mess with it? Other than the fact that now half the people on here will now be requesting a special tapered throat from their local 'smith . You will likely neck size at least, which will contract, then evenly expand the neck to a smaller size anyway. And lastly the reason a lot of new bullets won't go into a fired case is that the extractor/ ejector forces the case mouth against the chamber wall and reciever on the way out, deforming it slightly (sometimes not even slightly, more like a lot). With hot brass, it doesn't take much. Could that be the cause? Anyhow with the clearances you've got it doesn't sound like anything that would keep me from shooting it.

Have you tried measuring your bullets, or have you tried a different brand of bullets.

I have never seen it, but I suppose that it is possible for a bullet to have a slight bulge right at the base.

Have you tried boat tail bullets?

A little sampling from the last two outings. The paper is old computer green bar, those colored bars are 1/2" wide.

Sierra 100 Spitzer, 42.0 IMR4831, 3049 fps



Sierra 85 BTHP, 43.0 H4350, 3273 fps



Sierra 85 BTHP, 45.0 H4350, 3414 fps (three together with one of my famous thrown shots)



Sierra 85 BTHP, 45.5 H4350, 3454 fps




I dunno, it ain't broke, so I got a powerful urge to fix it...

Naahhh, think I'll just shoot it like it is.

I wonder if it could be caused by an interaction between the gas, bullet base, and neck outside chamfer, creating a swirl that compresses the mouth a tiny bit.

I would try a case with the outer corner left square, and try a different bullet.

Bruce

I had a few odd .30-'06 Federal cases, once fired factory loads from the same box. I annealed three very soft if not dead soft, heated til the necks were thoroughly red and quenched in water. Loaded those three and three as-is.

The difference in diameter was too small to measure reliably with plain old calipers. A bullet could be inserted into the un-annealed fired cases with almost no perceptible drag at the case mouth. With the annealed cases there was perceptible drag but little more than that.

Doesn't prove anything but makes Bruce's theory more likely than mine. Can't see how it would make a difference though it is an interesting curiosity.

It's certainly a possibility but it occurs with every bullet tried so far:
70 gr Sierra BTHP
80 Speer spitzer
Sierra 100 Spitzer
Sierra 85 BTHP
Hornady 100 BTSP

Also occurs with factory ammo from Federal (unknown bullet, my smith tried this one) and Remington 100 gr. PSP factory ammo. The latter are crimped in place but the mouth is definitely not outside beveled.

Until further evidence I shall attribute this to the spin throwing the demons off of the bullets before it leaves the barrel, so they migrate back to the case mouth.

Looks like it's doing a darn fine job spinning off those demons!!