Re: Muzzle Break on remmy
First, .655" is plenty of barrel to take down to .625" for a 5/8 x 24 thread.
If you have any plans to take the brake off, then I'd recommend something like the Badget FTE that uses a clamping system to hold the brake to the barrel. The problem I think you're going to have with the .655" barrel is that after threading you're only going to have .015" of shoulder for the brake to butt up against. If you want to turn the brake down to the barrel diameter, you're looking at having nearly nothing left of the brake.
If it was my rifle, I'd get the FTE or FTE-style brake and a thread protector just in 5/8" x 24 with probably a 7/8" OD for hunting purposes. Then you'll end up with the best of both worlds.