This worked perfectly. I needed to remove the factory brake off a CZ 805 BREN Pistol barrel. I had to squeeze it pretty good but the center slot worked for this relatively thin profile barrel. I'd say the barrel on the CZ 805 pistol is around an AR pencil diameter behind the gas block

Worked great to change the barrel on my Savage Axis 308. Don't be shy in tightening the vise though. You have to really crank it down.

This 2-piece clamp works great. It looks like they make these in really long sections, and cut them to this length.
I say this, because they arrived kind of rough on the ends but it's just a cosmetic thing. It doesn't affect the effectiveness of the tool.

Worked perfectly for removing muzzle device from Sig MPX (used the smallest barrel opening on the clamp which seems too small at first but fits perfect once clamped in the vise). Soak muzzle device in water for 24hrs to soften the Rocksett thread compound, then just separate the guns upper from the lower, remove the handguard, and clamp the barrel. No need to remove the barrel from the upper. Not much torque required to remove the muzzle device. Remember its left hand thread on this gun.
(Do not clamp the upper itself in a vice and apply torque to the barrel/ muzzle. It will likely end in tears.)
Didn't need the Rosin Grip. Obviously, just give the rubber surfaces of the clamp (and the barrel) a good cleaning before use for good grip and to reduce the chances of marring your barrel.
Prior to getting this clamp, I tried using the bessey soft jaws, but they were nowhere near sufficient to hold the barrel.

Just took apart an ar 10. This sucker worked GREAT!