Lock bolt hole question

[ToddCook]

I drilled my rear lock bolt ( l&r manton, 3/4 straight barrel) a tiny bit further forward than I wanted to. The hole is at the front of the breech plug lug, just into the barrel about 1/32 or so. With the plug being 5/8", this won't hurt anything will it?

[D. Taylor Sapergia]

I don't think it'll hurt anything, but why not drill it in the correct place and plug the wrong hole?

[577SXS]

Won't hurt a thing.

[mikeyfirelock]

I second 577’s reply.  I’ve done the same, and just gave the hole a little relief on the breech plug to make assembly easier.  Not a big deal.

[Stophel]

The hole is cutting into the barrel???

WAY too far forward.  Even if the gun doesn't blow up, you're still going to have major problems with the lock bolt head, sideplate, and lock panels.  Big time problems.   Plug the hole and move it back where it belongs.   You'll come out way ahead.   

While you're at it, cut that barrel and breechplug down!  A 5/8" breechplug is L O N G.  Especially for such a tiny barrel.  This is the real source of your problem.

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OH!  I guess you've got the lock inlet already, duh.  Well, things could still be moved around, but you probably shouldn't attempt it.  May be basically stuck with what you've got then. So forget what I said before, until you make your next gun, then remember it! 

[smylee grouch]

I guess I would agree with most of the comments so far as long as the touch hole/pan relationship is OK.

[mikeyfirelock]

Exactly where is the hole we are speaking of ?   If I understood correctly, the hole Is at the back end of the barrel, across the back of the threaded area of the plug, and not in the barrel or plug proper.   If we are speaking of another location then that is certainly a different situation.

[ToddCook]

like this

[D. Taylor Sapergia]

And where is the hole in the lockplate?

[B.Habermehl]

Todd, there’s no sin in where your hole is or danger. Especially if your using a small Siler lock and have a barrel with a 5/8 deep breech thread and plug. Depending on breech thread and lock, the hole can fall anywhere in the rear breechplug lug. BJH

PS The screw that holds the pan on a Siler type lock can force your hand sometimes on the lock plate bolt placement in relation to the breech lug.

[Not English]

Todd,

I agree the hole is too far forward. It is NOT a safety issue. I'd live with it and mark it up to experience taking note of other people's comments.

Dave

[mikeyfirelock]

If you need to move the hole to get your bolt a little farther back you can just plug the hole you already have with a short section of threaded rod of appropriate size.  Might want to solder or stake it in place if you will be drilling thru part of it to reposition your lock screw.    (  Dont ask me how I know so much about this. )

[Dphariss]

I was simply going to agree with Taylor and Stophel. But...
First the 5/8 deep breeching is not necessary. Outing the vent back is not that difficult, there are ways around this without shortening the barrel.
All three of these appear on British flintlocks. I use the bottom drawing most since the other two are more difficult and they Nock breech does not like cheap powder. i suspect the one pictured with the Nock is just as bad.
The bolt does not need to be moved for safety reasons.  Look to the strength of bolts, grade 2 and knowing the the nuts paired to them are relatively short. Then consider the pressure levels and the area of the breech exposed to the pressure. For example a 50 cal barrel with .010" deep rifling exposes about .212 square inches to the breech face. If we consider 20000 psi, very high poressure for a RB rifle then we have 20000 x .212=4240 psi to the breech face (you math experts feel free to correct me). While a 5/8-18  grade 2 bolt has a proof strength of over 14000 and a yield much higher than that. So making the breech of the barrel with more thread engagement than the corresponding nut is basically a waste of time.  In larger sizes like 3/4 or 7/8 the locking area goes up even if the breech recess is shorter then the nut for a given thread size. Even if we raise the breech pressure to modern brass suppository level of 50000 (which cannot be achieved with BP other than in closed bomb laboratory  testing, we still have a breech thrust of  only 10600. If you really want an eye opener look to the locking area of many modern brass suppository guns. While either case hardened or made of high strength alloys  that are heat treated the surface area is not all that great.
Grade 2 bolts are likely made of 1010-1018 low carbon steel.

[Stophel]

Can we assume that you have the lockplate inlet into the wood?  Or did you just locate the hole?  If the lockplate is inlet, is it FULLY inlet tight against the side of the barrel?  If the lockplate isn't inlet, you can fix everything and do it all right. No worries.