BLR Model 81

[TKO]

My lever has busted the firing pin. My gunsmith says he could fix it if Browning would sell him the part but its a part that is protected and only allowed installed by a Browning sevice center. My question is, I have found firing pins for the .308 on Gunbroker.com this is a .243 (same case) any reason one of these wont work? I really dont like the idea of sending the rifle out to be serviced, any thoughts?