Quoted: Before I bought my gun I did alot of research, the 7mm rum hase the best ballistics of them all.... don;t understand why more people doh't lean that way. |
Cartridge and rifle selection just depends. If recoil is important for shooting a long string, say a 40 shot silohuette match, the Remington Ultra Mags aren't going to get much attention.
Back to one of your original questions -
If the 160 AMAX is marginally stable in the 9 twist barrel, then it's reasonable that it falls apart in the 10 twist. Stability doesn't alsways degrade gradually or gracefully, sometimes the group opens and sometimes the bullets take a trajectory that looks like a sliced golf ball.
I've had two instances of unstable bullets. In a muzzle loader I tried shooting 300 grain Hornady pistol bullets; that produced a "group" at least 8 feet high at 100 yards. In my Contender carbine with 13.6 inch rifling, 52 grain bullets open to about 8 or 10 inch groups. Also, short 50 grain bullets shoot okay, but a Sierra or Hornady with a polymer tip will not not. None of these bullets key holed.
In another case experimenting with a 6.5 WSM that was not my rifle, the bullets never made it past the 300 yard berm. The wake showed a big looping unpredictable corkscrew shaped trajectory.