Lock Snail and Barrel Position

[Eric Krewson]

This came up on another forum, before I start filing I wanted a few opinions from the experts.

I have a GM 13/16 40cal barrel and a Chambers Late Ketland lock I am going to put in my current TN/NC gun build. The barrel has a long threaded breech that will put my touch hole and lock " down the barrel" mighty far if I use it as is.

I have 4 flintlocks from different builders(two I built) and time frames, the back edge of the snails on three out of four of them line up with back of the barrels.

Is this the most desirable position to achieve for the proper lock/ barrel configuration or do you fudge a little for more useable breech threads?

[gunmaker]

You only need 1/2" of threads in bbl. Eric.  May need to cut off little of breech to get that, MANY bbls. come threaded too deep.  If your vent hole is too far forward--may not be able to hit lock bolster with side lock screw....Tom

[JDK]

Yep.  Cut 'em, the barrel and the plug.  1/2" is more than plenty on a .40 caliber.  Enjoy, J.D.

[Dennis Glazener]

Eric,
Just my musings but I have not seen a snail breech used on a TN/NC rifle. Maybe some exist but I haven't seen one. I think I would be more inclined to make or convert a flint breech similiar to the ones shown here
http://www.trackofthewolf.com/List/Item.aspx/663/1 Would not use the tang or the hook but just the forward part and weld a TN/NC tang to the back of it.

If I remember correctly someone posted a similiar type breech in a discussion on vent liners. If I can find it I will post it here.

This is not the one I was thinking about but this is the type I am thinking about. Taylor made this one for a percussion rifle but it would work for a flint. http://americanlongrifles.org/forum/index.php?topic=34823.0
Dennis

[JDK]

My guess is he's talking about the fence on the back of the pan when he's referring to the snail, as he's using a late Ketland lock.  Eric???

Enjoy, J.D.

[Dennis Glazener]

Oh, I guess that makes more sense, guess the "snail" got me concerned Sorry, the shorter threads make more sense.
Dennis

[WKevinD]

I think others more knowledgeable than me need to comment on this but the way I've approached this is to  drill an undersized hole for my touch hole liner to mark the breech plug and file a V groove to the center of the breech plug. assuming you need to move the lock back less than 1/8". Any deeper than 1/8" and I would cut the breech/barrel back so that the touch hole was at the breech face.
I drill an undersized hole for the touch hole liner so that the final hole will not be pushed off making it egg shaped yet still mark the breech plug.


Hope this makes sense. (I know what I mean)   

[JDK]

I would avoid notching the breech plug if at all possible and it doesn't appear necessary here.  Even on a swamped barrel there should be enough latitude to set it back some this early in a build.

Having the full circumference of the breech plug sealed against the shoulder inside the barrel is preferable to having part of the breech threads exposed and possibly becoming a fouling trap.

During the confines of restorations or when someone simply prefers a longer breech plug due to a larger caliber or pressure concerns then a notch might be the way to go for them.

Enjoy, J.D.