Trying to put a free floating forearm and flat top upper on my 20" rifle. Got Brownells aluminum barrel vice clamp, however I can't break the barrelnut loose with the combi-wrench and 1/2 long ratchet. The barrel will spin in the vise even clamping it as hard as I can in my 12" steel vise. Even heated it with a butane torch thinking it may have been loctited, still not breaking loose. I'm getting a lot of torque on this thing, it's not that the jaws are not holding at all. Any suggestions?

You have one of two options.

The first is to get your hands on an upper receiver vise block, which will be the better option when it comes time to re-install the barrel. This directs all the torque to the barrel nut on the upper, and not threw the barrel extension pin as the only thing holding the upper from spinning with the nut as you apply pressure.

Or, using the barrel vise, apply a rosin compound (pitching bag powder) to the barrel before installing the barrel in the vise. This will keep the barrel from rotating in the vise.

You must have a vise.  I prefer reciever blocks.


If it is still stubborn, put the upper in the freezer overnight.

A buddy and I installed my FF RAS with the aluminum barrel block.  I'll be getting a receiver block.  Anyway, we tightened the barrel in the vise and I put on gloves and held the receiver while he turned the wrench.  To reinstall we screwed two boards together on each side of the receiver to get more leverage.

You're going to run into trouble when you install that FF tube. Hard to clamp the barrel when it's covered by a tube. [:\]

Get the receiver block and try again. Some barrel blocks need to be sanded down so they'll grab enough of the barrel. The barrel channel is too deep and the flats of the blocks touch when you put them in the vise. You may want to check yours.

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Thanks for the info guys. I finally got it, but not before the jaws slipped out of the vise under pressure, putting a crease in my forehead. As someone once told me (It builds character). Yeah right!

Well, at least it should get easier from here on. An action block (holds the upper in the vise) is the best AR tool you will ever buy.