Picked up a 700 stainless 308 over the weekend. I finally got a hold of someone at silencerco yesterday and he said 9/16-24 was the best choice for a Remington sporter barrel.
I am going to shoot it some at 24 inches before I cut it back. I think it will be interesting to have some real world numbers on velocity change when I cut it back to 20 inches.
Tried to point that out above with explanations why; good you got confirmation though.
If you have this question again in the future, here is what you need to know: a good barrel shoulder should be .040"-.050" tall, minimum. Double that for a diameter measurement on the barrel, and add it to the thread size - that's your minimum barrel diameter for that thread.
So, for a 9/16-24 thread (0.5625" OD) you'd have 0.5625 + .040 + .040 = 0.6425". A couple thousandths either way is OK, so your minimum barrel diameter for that thread is ~0.640". Make sense?
You can find threaded pistol barrels with shoulders smaller than that; it's not ideal but sometimes it's all you have to work with, certain 9mm barrels are a good example.
