GPR Breech Plug Size

[Hud]

Can anyone tell me the thread size and pitch of a .50 cal Lyman GPR breech plug??

 

[Hud]

No One here Knows?????

 

[Zonie]

It is most likely metric but the only way to find out is to pull a breech plug and measure it.

As removing a breech plug from a rifle can cause a great deal of damage to the barrel (and in the case of Thompson Center, void the lifelong warrenty) most people do not do that.

If you have a GPR breech plug, you should take it to a machine shop so they can determine exactly what the threads are.

 

[Hud]

Thanks Zonie,

I kind of thought that they may be metric