I respectfully disagree with the "toss it" folks. Why throw out a perfectly good patented breech when simply re-threading it for an oversize nipple is a simple (and less costly) matter?
I have to question if the breech is perfectly good? Removing many production breeches can damage the threads to the point that they may become unsafe.
Moreover, IMHO, someone who damages the breech severely enough to require a significant repair, may not be the correct person to make those repairs.
I have to agree with TOF and Mr. Adams, on this one. I vote for replacement of the breech.
IMHO it is a really bad idea for a novice to make a repair that can literally backfire on them...or someone else, causing permanent injury or death. Better to spend the extra bucks to fix it right, than try to save a few bucks cobbling parts together, in such a potentially dangerous area.
God bless