I have a Merwin Hulbert, Hopkins Allen Junior .22 rifle, The firing pin was broken when i recieved it but i am having a new one made. Does anyone know if the part of the pin that actually strikes the shell is round or square,(rectangle) as in todays modern .22 rifles? The rifle is a falling block .22, When you remove the block the is a round hole fore the fing pin, just not sure i sould go with a round profile or a square rectangle profile. Any help would be appreciated!!