Firing Pin Extension Nut ??

[Pastprime]

I have a .378" bolt head for my J series rifle on order from SSS and the very nice lady said I would also need a firing pin extension nut if I understood her correctly. Didn't think much about it until I took my bolt apart tonight and wonder now what it is for. Any idea's why I need this part?

[sharpshooter]

Your rifle uses long action bolt heads, and unfortunately .223 long action bolt heads are no longer available. The suitable replacement is a short action bolt head, which is .190" shorter in the tail than a long action. The extended firing pin stop nut takes up that space for the correct firing pin protrusion and the correct compression length on the spring.

[Pastprime]

Your rifle uses long action bolt heads, and unfortunately .223 long action bolt heads are no longer available. The suitable replacement is a short action bolt head, which is .190" shorter in the tail than a long action. The extended firing pin stop nut takes up that space for the correct firing pin protrusion and the correct compression length on the spring.

I believe I understand. The stop nut would just slide on the firing pin so it stops against the back of the bolt head sooner. Is that right..?

Edited to add:

OK, I did an hour or so searching and see how it works now. Need to do more reading about setting the firing pin protrusion and lining up the cocking button hole. Seem fairly simple but some of the explanations on the internet are a little hard to follow.