Originally Posted by winelines
Thanks. He is planning to match the leade to the Berger 180.
The only thing I can see wrong with a 1 in 8 twist is if you ever want to shoot light
bullets you run the risk of over rotating the bullets.
I ran into this with a 1 in 9 twist in a long barreled 7 STW that would exceed 3800ft/sec
and at about 3750 the 140s would come apart as soon as they left the muzzle.
The best shooting 1000 yard rifle I ever had was a 30'' barreled 7mm rem mag loaded very hard
( 3348 ft/sec with a 168gr SMK) and it was a 1 in 9.250 twist.
This rifle loved the 175gr bullets also.
A 1 in 9 is the only twist that I use on all of the 7mm that I build and they all shoot sub 1/2
MOA groups in a wide variety of bullet weights. A 1 in 9.250 may just be the perfect twist
for the 7mm bullet but the 1 in 9 is the most common and easiest to find.
As to the free bore issue; most of the new magnums have more than standard free bore
because of higher saami pressures required to achieve the velocity in them. (Like the WSMs,
WSSMs,SAUMs, RUMs and more. and if you short throat them then you cant safely use
factory ammo or load as hot because of pressure so you lose any advantage that the new
Accuracy is directly effected by minimizing head space on belted and/or long throated
I have never shot the 180gr burgers in any 7mm because of the seating depth issue (They
like it close to the lands) and the loss of velocity.
The real hot rod in 7mm is the RUM with a 26"barrel the 140gr is the contender for the worlds
flattest shooting factory round. (3570ft/sec in a 26" barrel) and it has lots of free bore to keep
And if you want to shoot bullets that heavy (180 ,190 grs)I would look at the 30 caliber
Just my 2 cents
J E CUSTOM