Seating Breech plug

[ky_man]

I'm working on my new pistol project, and I have a question about seating the breech plug. I managed to get it reasonably close, after about 1 hour of alternatively filing the breech plug face, then the barrel face. When I got the plug, it was about 1/4" too long, after filing it's 3/8" long, seated right up against the rifling, and mirror polished.

I ended up with a good fit, but there's 0.005" by my feeler gauge between the top of the barrel flat and the top of the plug tang flat. I have some metal to work with (1/8") on the tang, can I peen it over and close this gap, or am I stuck with it?

This is my first go, so be easy on me. The plug fits nice and tight, not sure how much torque I actually put on it, but I wrenched it down pretty good. The bottom of the tang fits perfect, of course :cursing:

 

[TANSTAAFL]

I ended up with a good fit, but there's 0.005" by my feeler gauge between the top of the barrel flat and the top of the plug tang flat. I have some metal to work with (1/8") on the tang, can I peen it over and close this gap, or am I stuck with it?

:cursing:

We have had threads on the subject of fitting breech plugs, here is my post on one. You can view the entire topic at bottom of the post to get input from others.
[url] http://www.muzzleloadingforum.com/fusionbb/showpost.php?post/297248[/url]/

 

[bob308]

make a washer out of .006 brass shim stock tighten it up the fill it down to match the flats. then it will look like a brass in lay.

 

[dlemaster]

Ky Man
If I understand you correctly, you have the flat of the barrel and the flat of the tang lined up, but there is a gap of .005 between them. You say you have about 1/8" of metal to play with on the tang. Do you mean that the top flat of the tang is 1/8" above the top flat of the barrel? If this is the case, indeed I would just peen the metal on the tang to close the gap. Then file the rest of the tang flush to match.

Regards, Dave

 

[rich pierce]

Couple of things. If your plug is really only threaded for 3/8", that's short. Quite short by any standards. Not trying to rain on your parade but you're just getting started on a build and getting this part right, tight, and safe is probably the most important part of the build. I would not go under 1/2" of threads, good threads, on a breechplug. I might if it was a very small caliber, but if .40 or larger, I'd want more threads. So you may want to consider deepening the threaded breech on the barrel and fitting a new plug with 1/2" of threads as a good safe minimum.

If you decide to stick with where you are and want to close that gap, you can peen the tang. It will close up that .005 gap.

 

[ky_man]

Dvlmstr:

Yes, you read me correctly. It seems the metal is soft enough to peen, and there is enough to play with so I should be able to file the peened surface flat and leave no gap.

As for the breech plug length, I'll send pics and proper measurements tonight after I get home from work.

I realize this is the most important step in the build, and I plan to proof the barrel before use for safety (double charge, double load) As I said, this is my first build, so I'm trying to take in and learn as much as possible.

Also, I read in 'Recreating the American Longrifle' that the threads can be coated with vaseline and powdered graphite (as anti-seize). If these are load bearing threads, wouldn't it be safer to keep them clean and dry, as head bolts in an engine are kept? Since I mentioned engines, to breech plug threads have any 'stretch' factor associated with them that might make installation/removal unsafe (I have never really followed this rule with my cars, I just run a die down them, clean and re-install!)

 

[flintlockmdj]

Since this is a pistol you will be (or should be) using light to moderate loads. If your breechplug is 5/8 X 18 with a 3/8 length you should have 6 to 7 threads in contact. I would not shorten it any more. Ether pean the bp to fit or make the brass spacer will fill the gap. Hope this helps.

 

[ky_man]

At 18 TPI, 7 threads is ~3/8" so i should be OK. I'll have to look at the actual piece tonight, I can't rememeber the measurements off the top of my head.

 

[MSW]

i would go with the brass washer (as opposed to peening) ... if you haven't read it, go ahead and check out the thread- it's got some good advice. you should also consider anti- sieze goo in case you ever need to get the breechplug back out.

good luck!

msw

 

[dlemaster]

Ky Man
Everyone has their own ideas of how things should be done. I will offer to you my own personal opinon and what I would do.
First, I would just peen the metal to close the gap, you're only talking about .005". To me making a brass washer is more work than peening it, and for me to use a brass washer would just look hokey. I would never be satisfied with it, but to each his own.

As for lubing the threads on the breech plug. I would never install a plug without putting an anti-seize compound on it. Without a lube you must overcome the friction of the threads to seat the plug and no lube encourages galling of the threads. All of the top builders in the country, that I know of, all use some kind of treatment on the plug threads. It will make removal of the plug much easier at a later date.
The only thing you have to watch is that the lube can seep out between the barrel/tang joint and affect your attempts at browning or blueing the barrel. To avoid this, I use the compound sparingly and I thoroughly clean the breech area with a good solvent after the plug is installed.
I hope this can be of help to you.

Regards, Dave