Breech plug fitment, lathe set up?

[1BadDart]

When you guys fit a breech plug, where do you set up your indicator? On the threads, the shoulders or the face of the tang lugs? My breech plug tightens up nice but has a .003" gap between the top of the tang and barrel.

 

[Phil Coffins]

I use a bore sized pin to indicate on In the barrel, if facing a plug it’s threaded into a piece of stock to cut.

 

[1BadDart]

How do you cut the shoulders? If my math is right, I need to take .007" off the face of the plug and .003" off the shoulders of the tang.

Thanks, Justin

 

[Kansas Kid]

Bore size pin in bore mounted in a 4 jaw independent chuck. I mount the breech plugs in a large round split threading die and then a three jaw scroll chuck. Die adjusting screw backed out of course. Use a parting tool to skim the shoulder.

 

[Kansas Kid]

.003 might just crush in. Chamfer the starter thread a decent amount to deal with the imperfect thread in the bottom of barrel thread. Or just turn the starter thread on plug to root dia.

 

[1BadDart]

Thanks guys. I'm setting (breech plug) up in a four jaw chuck, when set up on the threads it was within .001" but was .010" on the two tang surfaces.

My thinking is to take .003" off the face and try it again and see if the tang is still in time with the flat. If not, I'll have to cut the face and the tang surfaces.

Has anyone ever fitted a piece of SS shim stock on between the face of the plug and the shoulder on the barrel? I talked to a guy a few years ago that told me he did this to make cleaning the breech face easier.

Thanks, Justin

 

[1BadDart]

It's finished. It only needing .007" off the face and .004" tang shoulders, so I just used a file. Took about 20 minutes, black sharpie on all three surfaces, install, remove and check contact, file and repeat.

 

[Kansas Kid]

Polish the the plug face up real good and you won’t need a bore light as it will reflect when you shine a light down it.