Originally Posted by jasonprox700
I recently aquired a 7mm RUM that has the J Lock bolt. What exactly does this do? Will I gain anything by swapping it out? This gun will be used for a .300 RUM project, so any suggestions would be appreciated.
It's a lock that physically locks the firing pin. It's just another thing to go wrong at the worst moment.
For about $50 you can replace it with an aftermarket assembly from Callahan, PTG, or others.
IMO, you'll get better and more consistent primer strikes and shorter lock time if you replace the J-lock.