If the brake is not screwed on, you may want to thread the barrel of your SAR-1. ATAK, Inc. rents the threading device for $23 shipped to you and you pay to ship it back to him. If you are interested in renting, you can go to this thread to contact him: http://www.gunsnet.net/forums/showthread.php?t=317428
. The thread will be the authentic 1:14 LH thread.
Several years ago, I threaded the muzzle of my SAR-1 and itís not that difficult to do. However, if you don't have access to a vise to hold the rifle in a secure vertical position, you will need a friend to help by holding the rifle steady while you do the threading.
If you do thread the barrel, be sure to use a U.S. made muzzle device so that you stay within the 922R regulations.