Touch hole position relative to breech plug?

[brokenhand]

I have only built one rifle from a plank.  It was my first flintlock and I built it so the 1/4" liner clears the front of the breech plug face.  I also have a Chambers York rifle.  The touch hole liner intersects the end of the breech plug.  I had to file a sort of tapered little cone shaped ditch to the middle of the breech plug face.  I am ok with this and do not think it is a safety issue but,  Here is my question: If you are not trying to make an exact copy of some  particular rifle made in such a way, would you drill for your touch hole liner so that it clears the front of your breech plug?  Or would you lay it out so the actual hole is maybe like 1/16' in front of the breech face.  What I am wondering about is the area below the breech face. That groove I filed across there. It doesn't seem like one could get it properly cleaned very easy. Anyway, I am working on a winter project and questioning this. I do like the way the back side of the pan is sitting right at the actual back of the barrel on my York. Is this what they actually mean when they talk about the wrist architecture, or part of it? Thank you for your thoughts. I tried to do a search. Sorry if this is repetitive.

[smylee grouch]

One thing I would consider is if the vent gets a little too far forward and you dry ball a load your ball might obstruct the vent to the point of not being able to get 4f in behind the ball to pop it out. Also if you try to use a ball puller you can expand the ball into the vent hole as you screw the puller screw into the ball.

[Ky-Flinter]

Or would you lay it out so the actual hole is maybe like 1/16' in front of the breech face. 

Yes.  Ideally I like the touchhole to be just in front of the breech plug, so that the breech face seal with the barrel doesn't have to be interrupted.  That being said, the little groove you have in the breech plug face isn't the end of the world.  To clean that area after shooting, remove the barrel and put the breech end in a coffee can of room temp water and some dish soap and pump water in and out with a patched cleaning rod.  I follow that with WD40, then Barricade.

-Ron

[Adrie luke]

Hello



Adrie

[Marvin S]

Might just be me but I detest the notch. If I get a gun with a notch I remove the breech plug and counter bore it flat. Every one I build will clear the breech plug. Breech plug can be removed without removing the liner. If the touch hole is too close to the breech face it don’t take to much fouling to plug the gun up.

I think the placement predetermined by swamp barrel precarve kits is just a throwback from when liners were not used so much.

[577SXS]

I agree with Marvin, I don't like the flash hole at the edge of the breach plug. It would foul much worse being that close to plug. This is why I stopped building kits. Several of the kits I built had lock mortise too far back. I like the edge of my liner to be just forward of the plug.

[D. Taylor Sapergia]

I use barrels that have a breech diameter sufficient to allow the liner to be installed so that the vent crosses the face of the plug + 1/16"...the liner does not protrude into the plug - just the barrel.  Sometimes I have to use a ball grinder from the breech end of the barrel to make the liner flush with the bore.

[brokenhand]

Thank you all for your replies. It seems I am not the only one who wonders about such things.  D. Taylor, I guess your answer was what I was looking to find. Basically an absolute that would always work. Marvin, I also liked your answer. I called it a groove, you I believe are calling it a notch, but neither of us like it. I think I will make mine so the liner clears the breech face. I also never considered fouling to plug the gun up if too close to breech face.  My first flint gun was far from perfect, but I never had any ignition or cleaning issues and that was a really good thing.  Adrie, thank you for your effort, but that description is to locate the lock to the touch hole. I was wondering about touch hole to breech plug.

[EC121]

The old guns usually had shorter breechplugs, and the fence could line up with the end of the barrel.  Contemporary barrels have 5/8" deep threads.  Also if you look at some of the originals, the fence lines up all over the place. 

[Richard]

I’ve wondered about this myself. I am new to building so my writings may be more looking for confirmation than providing advice. If I’m wrong, I need to get corrected.

So… if I plan for the external 1/16 touch hole of the liner to be correctly positioned in the pan, then the position of the lock in relation to the barrel dictates the resulting internal position and the effect the liner will have on the seal of the breech plug. 
I envision 3 general situations.
1. Position lock/barrel, such that the liner threads do not intersect the seal of the plug face. This could give the look of the fence being quite forward of the barrel breech end.
2. Position the lock/barrel such that the liner’s internal ID (the cones edge) is in line with the face of the plug. This improves the relation of the fence to the breech, but the liner threads will kiss into the face of the plug and break the mating surface.
3. Position the lock/barrel such that the fence is or almost inline with the barrel breech end. This would put the edge of the cone behind the face of the plug and the plug should then be dished out.

Recognizing there are always exceptions, given different barrel, lock, plug geometry.
Option 2 is what I have been doing so far.

Richard

[Scota4570]

Hugh Toenjes breached guns with the liner through the side of the plug threads threads.  That moved the liner as far back as needed to put the fence even with the back of the barrel.  I like the idea but not with a standard 5/8" plug.  If the plug were 7/8" long the amount of active threads would be the same as the standard set up with a 5/8" plug, using a 1/4" liner.  Does anyone do this?  Is there any downside for the finished rifle?  Fouling issues? 

[Not English]

I will mill the breech down to a 1/2" possibly, but no smaller, and go from there. It all depends on what lock you will  be using. The distance from the fence to the middle of the pan will help determine the depth of the breach. You will have to fit the breech plug by hand. I have never had a problem with a half inch deep breech. You will also need a bottoming tap to finish the threads to the shoulder of the breech.

[sdilts]

Rice barrels have 1/2" deep breech.

[flehto]

The plug threaded length of a Rice bbl is 1/2" and w/ the 1/4 dia White Lightning liner, the TH center is 5/32" from the plug face. Using this dim fully  exposes  the rounded cone of the liner  to the powder. ......Fred

[Marvin S]

I suppose if one is concerned about lock fence and breach relationship, then counter boring/ spot facing the breech plug face is a good option. It gets rid of that fouling trough that’s so had to clean.

I do mine in a 14” Clausing lathe and start with a center cutting end mill and finish with a micro boring bar.