you will first have to determine if they are both "newer" style or not. Where is the bolt release lever on the FCP? If its on the side of the receiver, then it is the "old" style, the 10tr has the new style with the lever/button in front of the trigger guard.
Then, if they are the same, determine what the bolt spacing on the stock/receiver is. The 10tr has a detachable mag, does the fcp?
That's an awful lot of trouble for just a threaded muzzle and factory tactical bolt knob. You don't really "need" the brake for a 308, and an aftermarket bolt knob is a 2 min job with just an hex key.
good luck.