I have two rifles which fall into the OP's comments on barrel length. The first is a Remington M660 that has been somewhat modified, mainly with a lighter synthetic stock. Barrel length is 20". I made the longest shot I've ever taken on a big bodied Nevada Mule Deer, 460 paces. Bullet was the handloaded 150 gr. Sierra, velocity unknown.
Rifle #1 is a Ruger M77 RSI with 18.5" barrel. target was an Arizona Mule Deer up in the Kaibab National forest about 250 yards out. Bullet was the 165 gr. Speer Hot Core at 2550 FPS. Dunno what it would be in the 20" M660 but when tested in a 22" Winchester M70 the velocity was 2610 FPS. I'm guessing the M660 speed falls somewhere in between the two.
Both rifles are chambered to the .308 Win. Both run about 1.0 to 1.5" with their chosen load.
I can't Speak for other copies of the RSI, but somehow I ended up with three of then cheap because their previous owners could not get any kind of decent groups from them. Turned out they were right in the short term but I was stubborn. I knew 1.5" or less might be attainable so I set that or better as the goal. It took a hair over two years to reach that level of accuracy and but some very good luck the load worked in all three rifle. Some tinkering with metal removal from the nose cap brought groups down to 1.25" most of the time with an occasional 1.0" or 1.5" but nothing worse as long as I do my part. On game, I try to get within 250 yards or closer. If conditions are perfect I might try 300 yards but that's as far asI'll got with that 165 gr. load.
Paul B.
