Re: 7mm RUM/180gr Berger Disappointment
i've loaded for this combo but with a different powder(872) and a 30" 7 twist barrel. i shot them at 3250 and the jacket was strong enough to take a 7 twist with 3 grooves.
this reminds me of a gun a local smith built to compete at 1k back in the 70's. a 30+ pound monster, full bench, finally ready, back to the range and you could have bought that gun for $5 when it didn't even shoot an inch at 100 yards. everyone was talking about what they were gonna do with this POS. i asked if i could shoot a group with it and of course they said go ahead shoot em all up, didn't matter any more. i took a target out to 200 yards and got quite a bit of laughter from the gang. lined it up and just started pulling the trigger. easiest gun i ever shot, it just layed there like some of my old girlfriends. after i shot 3 i was sweating because i could see the group was almost a hole in the paper and i had never done this before. when i put the last 2 in the same place, i was pretty happy but no one even came over to look at the spotting scope. they asked if all the holes were on the paper. when the smith looked and told them the group was less than a 1/2 inch they laughed at him. he came in 3rd place for the year with that gun.
the point to all of this is bullets aren't always stabile at 100 yards. sometimes you have to shoot at farther distances to see how accurate it really is.