Heavy bullets in .223 rem

[petenz]

I have a remmy 700 .223, 1:12 twist and 22" barrel, I want to rebarrel it with a 1:8 twist 24" barrel to use the 69-75gr class bullets, what sort of results can I expect, in terms of velocity, terminal performance (varmints)

 

[anachronism]

The first thing is going to be bullet selection. I've had poor results with heavy weight 223 bullets on varmints because the bullets usually don't expand. They do however penetrate better, probably not what's needed for prairie dogs, but potentially better for fur bearing critters like fox or coyote which have greater body mass. I was going to build a fast twist 22-250 but talked myself out of it because I realized that while it would be a great target caliber, it could likely be inferior to a 1:10 because of the bullet limitations. All I was doing was designing an inferior low-end .243 replacement as far as game performance was concerned. I suppose custom thin jacketed heavyweight bullets could make the project more practical. I have a couple of friends who shoot a lot of .223 with 77 gr loads, but they only use them for targets, which they do very well at. If they take these rifles hunting, they limit themselves to 50 to 55 gr bullets anyway. The military uses 77 gr matchkings in 5.56 (.223) in combat because the bullets aren't designed to expand, which would be a violation of the Hague Conferences agreement. The heavy bullets would be a great medium range counter-sniper load in an accurate bolt rifle.