Breechplug thread length

[Habu]

Please excuse me for asking this, I just wanted to double check. 

I'm in the process of doing drawings for a future build.  Barrel is a .62 cal Colerain.  If the breech is fit properly, there's no problem with a 1/2" of threads on the plug, is there?

Thanks

[Acer Saccharum]

I've seen originals with less, but I'd not go less than 1/2.

Tom

[Habu]

Thanks! 

I was setting 1/2" as minimum.  What I'll probably actually do is shorten the plug to 9/16, then breech the barrel as usual (fitting plug face to shoulder, etc).  If everything goes right, I'll have a nominal 9/16" plug; if the Colerain stamp winds up on top, I'll have a little extra I can remove to put it on the bottom three flats. 

[Herb]

Rice barrels are breeched for a 1/2" plug, and that is a nice length.  Much better than 9/16" like Green Mountain barrels.

[Brian]

Make sure you measure your barrel and the actual plug before you lay things out.  I got caught that way once.  I assumed it was a 1/2" plug and it turned out to be longer.  By then I had set out the lock and flash hole.  Not the end of the world, but not something I was happy with.  My own mistake.

[Habu]

Brian, I've had little surprises like that too!  That's why I'm still at the sketching stage.  Well, that, and because I've never built a jaeger before, or a rifle with a bore this large, and I'm still working out some things. 

I'm making haste most slowly on this one.  It will probably be another month or two before I settle on the basic details.   

[Dave Faletti]

I prefer the deeper thread depth that Green Mountain uses.  I can always trim the barrel some if need be.  I like to use all the threads on a breach plug. It does depend on the plug diameter.  I like the thread length equaling the diameter if I can get it.

[coutios]

  Just to clarify for those who are reading... Those that want a 1/2 inch plug are you speaking of the overall plug length being 1/2 inch or 1/2 inch of full thread engagement.. there is a difference..

Regards
Dave

[Don Getz]

Just a little something to think about.   Many years ago we did some barrel blow-ups.   We took pieces of barrel and breeched both ends, 1/2", which has been our standard.   Made a hole for a fuse, and blew them up.    Barrels opened
up like a banana, but, would you believe it, both breech plugs were still there...........Don

[Habu]

  Just to clarify for those who are reading... Those that want a 1/2 inch plug are you speaking of the overall plug length being 1/2 inch or 1/2 inch of full thread engagement.. there is a difference..

Regards
Dave

Speaking just for me, I was referring to that portion of the plug which extends into the barrel.

I just pulled the breechplug from the barrel on my current project (.54 cal, threaded 3/4-16).  The part that extends into the barrel is around .51" long.  Not being a machinist, I'm not sure how to describe the threads, but it looks like I have almost 7 complete threads on the plug, from the face to the relief cut at the back. 

[Chris Treichel]

Ok, thought it better to reopen an old thread than start a new one since this one already has some of the information I was looking for. 

So for a sanity check since this will be dealing with some higher preassure than a round ball situation... combining an English patent breech from TOW, platinum lined nipples (still working on a source), and a 1 inch 4140 Green Mountain .45 barrel (designed to shoot 45-70 black powder cartrriges). I will be shooting a paper patch bullet.  The barrel and plug are 3/4 x16 and the patent breech is threaded for .50 inch, the barrel is threaded .7 of an inch deep. Do I go with the plug that is threaded .5 inch as sufficient and shorten the barrel or do I need to get a longer plug?

Probably need to do some more reading... Yes, still doing research before I actually go ahead.
 
Any input on this?

[Bob Roller]

This type of rifle is something I can really get into. The barrel you mentioned is a fine one. I built a good representation of an Alex Henry with a GM barrel beginning it in 2001 and finally testing it in 2003. There is an old axiom that says the maximum strength of a thread is reached when it is screwed into the depth of its diameter. A 3/4x16 diameter should be 3/4's of an inch long
but then,that bullet will move forward much easier than the  1/2" of threads on the plug will move backwards.
Contact Rod England at<rtengland864@aol.com>.He has the tooling for the late Don Brown's Alex Henry and the breech Don offered was WAY better than the TOW item.
Years ago I posted on another list that these English types of rifles are NOT Kentucky rifles and a good bit of planning and seeking of proper parts is needed. The slip shod methods that are seen in a lot of round ball guns will get someone hurt or worse with these guns. NO drum and nipple should ever be used and I have an article that was copyrighted for me by David Minshall of Research Press in England that addresses this issue.
Contact me at <wvgzr@webtv.net> and I will give you the article if you want it.
Rick Weber in Lenoir City,Tn has been a source of platinum base nipples and may still be.

Bob Roller

[Chris Treichel]

Thank you, that is exactly what I was looking for.  I will send you an e-mail.

[T*O*F]

Chris,
Will your gun be a straight stock or a pistol grip?

[Eric Smith]

What is the standard for  breechplugs from Colrain. Are they all 1/2 inch or some longer?

[Bob Roller]

The breech plugs for a round ball barrel are nothing at all like the ones used in these bullet guns. They are related by being threaded and that's all.

Bob Roller

[Chris Treichel]

Straight rifle with schuetzen furniture.

 

[T*O*F]

Chris,
I don't know what your building experience is, but either the schuetzen or the Rigby are advanced projects.  There are very few matched component sets available and you can't just slap a bunch of components together like with a regular ML.  To build one properly; ie, a bullet gun, there are special requirements besides just the barrel and breechplug that are not found on other guns.  Knowledge of these requirements and a good set of prints locating your components is almost a must.  You might have to have some parts fabricated.

While guns can be made using a 1" barrel, they are somewhat of a handicap as available components are really for 1-1/8" or 1-1/4" barrels.  I've done a couple and they are a PITA.

[Chris Treichel]

That is why I am doing the research and appreaciating all of the responses I have had.  This site is a gold mine and what little I can do will be by standing on the shoulders of giants (or having apples fall on my head).  Well, back to the books.

[cmac]

The original I had put a link to in the antique collecting section under western NY attic find, had maybe a 1/4" of threads and I'm guessing maybe 1 turn as most of the early pieces did. Kinda scary but its still here. I too consider 1/2" a minimum

[greybeard]

Just a little something to think about.   Many years ago we did some barrel blow-ups.   We took pieces of barrel and breeched both ends, 1/2", which has been our standard.   Made a hole for a fuse, and blew them up.    Barrels opened
up like a banana, but, would you believe it, both breech plugs were still there...........Don
[/quote
Don; Do you recall Bill Large machining 1 thread off of a plug and likewise the barrel. loaded a regular lode and fired it. They kept it up untill the plug blew out
. there was inly 1 1/2 threads left on the plug when it let go. I seem to recall it was a .50 barrel and the results were published in Muzzle Blast.
Bob Reader

[Chris Treichel]

Yes Sir, this will be my third. First was a TOW fusil, second was a bunch of parts and a half finished stock (barrel inlet and some rough work done) I got from Kennedy. This one I want to do all of the wood work and already have a stock blank that will work.