Use a product called JB Weld and fill in the holes. Just degrease real good, and mix up the JB Weld. I've fixed engine blocks and motorcycle crank cases with this stuff!! you could put a dowel rod in the bore of the brake to make sure the JBW wont ooze in to the bore. Just spray some WD 40 on the rod. Should work.

Hey Dago,
Is it a screw on brake, or did someone drill holes into the barrel? I bought a rifle for my unit a few months back. It had a muzzle brake. My gunsmith made a thread cap. It cost me $30.00. Now, when someone visits, and wants to shoot, I can give them plugs + muffs, and let them shoot with low recoil. For hunting I just put the thread protector on and check the zero.
JCN

A hacksaw in a miter box followed by a good home brewed recrown would definatley "fix" the problem and would take no more time than dilly dallying around with JB weld. It would be safer too.