I'm going to have Montana Rifle barrel two of their short actions for 7mm-08 and I don't know what the optimium twist rate should be.

They'll be used with factory ammo, almost exclusively 140g. bullets.

Thanks, Rob

1 in 9 is standard factory twist for 7MM. If you want to go with heavy bullets only you might go with 1-8 or for 120grain or lighter a 1-10 would do. But for overall general use (factory with 140 grain as you say) the 1 in 9 would be best.
IMHO
AE

Ain't tryin' to start anything here but 1:10 will do fine for 140 gr bullet or less. The 1:9 is required for the heavyweights in 7mm, but 140 ain't it. The original 7x57 shot 190 grain bullets with a 1:9 +/_ twist. 1:10 will stabilize Hornady 154 gr bullets just fine.

How long is a 140g pointed bullet and what about a 160g.

The MRC website has a link to a twist rate calculator but you need to know bullet length.

Thanks, Rob

[ 06-06-2003, 05:04: Message edited by: Recoil Rob ]

My factory 1/9 does very well with 154gr round nose bullets. Haven't tried 154gr spitzers tho.

I believe my old M788 Remington in 7-08 is 1 to 9.5" from the factory. Has shot everything from 100-170 grn. bullets OK out of a 18 1/2" barrel. BM

[ 06-06-2003, 04:44: Message edited by: BlueMoon ]

I see that Montana does offer a 9.5" barrel.

Jack of all trades or master of none?

Seriously, is this a good choice?

Rob

One in 9.5 would be great. A 1 in 11 would do for 140's, but you would be in trouble with anything heavier. With a 160 Nosler Partition this round is competent on Elk out to about 200 yards. Just go with 9.5

I have shot 160s in a 12 twist with good results though I think this is the limit. The 7x61 Sharpe&hart used a 12 twist and was loaded with 160s by Norma.
It is unlikely you would see any difference in performance between a 9 and an 11 with anything 160 and under. Regards, Bill.

The twist rate you select should partially depend on what other rifles you have. You mentioned that they'll be used with factory ammo, almost exclusively 140g. bullets. I have a 7-08AI that wears a Shilen barrel with a 1:11 twist, because I knew I wouldn't be shooting anything heavier than 140gr in this rifle. I believe that 140gr bullets are ideal for deer in the 7-08. If I need more horsepower than the 140gr bullet from a 7-08 offers, I'm probably shooting at something larger than deer, and would be using more gun, not just a heavier bullet from the same cartridge.

[ 06-06-2003, 09:25: Message edited by: SST ]