Author Topic: 30-30 bore diameter !?! (Read 1090 times)

pascalp · « **on:** May 14, 2005, 09:09:25 AM »

I own a H&R model 258 (combo 30-30, 20gage) from 1982, bought second-hand quite new.

I was worried by the rifling of my 30-30, look really thin.
I slug the barrel today and found: .305 . I've clean-it thoroughly (i think) so there is no lead or copper deposit.

Wich is the usual diameter of yours ?.

I shoot cast bullet, actually sized .309. So i think to change the mold or size them according to the barrel diameter ?.

James B · « **Reply #1 on:** May 14, 2005, 02:30:04 PM »

Did you measure the groove diameter? If I recall the bore diameter should be around .300-302 and the groove diameter should be 308. Barrels can very a little for machine tolerances but that should be close. A cast bullet of 309 should work fine. However if your cast bullets are to hard and the rifleing is to shallow the accuracy could suffer.

pascalp · « **Reply #2 on:** May 15, 2005, 12:24:38 AM »

I wasn't clear with my measures :oops:
.305 is groove diameter, the maximal diameter of the slug. I think that i miss .003" to be at the "usual" .308
I'm afraid that isn't dirt which fill grooves but that the barrel was made with used tools.
So i'll have to adapt my bullets. And due to the thin rifling, avoid hot load. Actually, seems to shoot well with light loads, i haven't achieve my discovery of the rifle and the caliber.

Mitch in MI · « **Reply #3 on:** May 15, 2005, 03:53:02 AM »

Were there any tight spots, or was the whole barrel .305"?

pascalp · « **Reply #4 on:** May 15, 2005, 08:00:13 AM »

Good question Mitch,
i haven't think to tight spot because rifling seems thin all the way, easy to see (for me) with barrel in hand.
To be sure i push a slug, 1" from the barrel and another from the chamber. The barrel is good !, both are .305".
By the way i try to clean the barrel one more time, with "Bore Scrubber" and bronze brush, without change. Maybe just more clean.