Originally Posted by smallbutfierce
Been looking into building an AR. I hunt coyotes and deer, so it has to be able to effectively take out these two animals. I have been looking at the .223, and as much fun it would be to shoot, I think I want more. I am interested in both .243 WSSM and .25 WSSM. Curious as to what guys who have shot these in AR form think about the ballistics.
223 WSSM - Much more case capacity than a 22-250. Barrel life is limited. Like other high velocity "varmint" cartridge it can cause explosive surface wounds.
243 WSSM. - Similar*to a 243 Win in a standard short action magazine. Low wind deflection.
25 WSSM - Similar* to a 257 Roberts in standard short action magazine.
300 OSSM - Similar* to a 308 Win in a standard short action magazine. Highest short range energy. Longest barrel life. OSSM brass is made by necking up 25 WSSM brass.
*None of them can shoot heavy low drag bullets limited by magazine length. the 308 OSSM is limited to 150 grain BTs. All require special magazines for use in an AR-15.
I'm not sure what you mean by "build". You can buy uppers which fit standard lowers from Olympic arms. I don't know of anyone who sells complete barrels, barrel extensions, or bolts separately. Accuracy Systems offers custom uppers.