I remember reading here that the 308 used a 5/8-24 thread and I thought the 223 used a 1/2-28. I know the new Hog Hunter Model is threaded that way and I believe the 10/110-BA's are threaded 5/8-24 also. I think only the "Adjustable" Savage Brakes are threaded oddly, using a 9/16-28.

I am 99% sure on all of that, but...