Originally Posted by Bodywerks
6.5 or 7saum would do quite well on a 24"bbl. Should be high 2900s velocity with the 160ish weight bullets on the 7mm, 3200+ I'd guess on the 6.5 140gr bullets...screamer!
only guys I know shooting the short mags, use a 26" longer barrel. Case capacity is in the 30-06 area like the 284 case. Might get by with a 24" barrel length (to get max use of the case volume). On the otherhand a lot of fellows are shooting the 30-06 with a 22" barrel length. I think the 6.5AI might do OK with a 23" barrel and 1 30 grain bullets. The 6.5AI ought to push a 130 grain bullet into the 3100fps area with a very stiff load.
The 57mm improved case will come in slightly less than the 64mm Springfield case. To me a 60mm improved case might be the ticket. Say a 1.85" shoulder length. That one ought to put you close to 3200fps, and cases can be formed out of 25-06 brass (easy to do). Will come in just slightly less than the 6.5/284, but your still going to have to have a long action.
In a short action, and wanting big velocities, your sort of stuck with a long barreled short mag. The 25WSM necked up to 6.5 (can't remember what they call it) might be the ticket. It'll be slower than the 6.5WSM, but work better in a 23" barrel length. I just think the 270 necked down to 6.5 in the WSM will not work as well. I can see an easy 3000fps with a 130 grain bullet. Don't think you can get that out of the 6.5/284 in a 23" barrel without simply blowing a bunch of unburnt powder thru the barrel. Even the .250Ackley would do well. I've shot several 6mm Remington's with 22" and 24" barrels, and with lighter bullets they did OK. The 6.5Ackley is built off that case. The real issue here is the 9" long suppressor. I think your better off without it.