Touch hole drilling question

[jafo20]

Hello,

I have my breech plug fitted and was reading in Dixons book about the touch hole. My question is do you drill into the breech threads to install a liner? The book says it is ok..just seeing what you guys do.

Thank you for your time

[Nate McKenzie]

If you drill into the breech threads, you must notch the front of the breech to create a flash channel. This also creates a place for fowling to collect which is very hard to clean. I'd rather put the hole right in front of the breech. Don't forget to allow room for the liner threads if you are using a one.

[Dave R]

I AGREE With Nate !

Dave R

[Dr. Tim-Boone]

Me too.

[Dphariss]

This depends on the installation and whether you are making your own liner or not.

This liner seats about 1/4 diameter on the breech plug


This is another way and is similar to some English breeches from the past.



Notching the breech face is not a good idea. Its been done for a very long time and it works. But its still a bad idea.

I have been known to deepen the breech plug threads and go with the system shown in the drawing.
Dan

[Dr. Tim-Boone]

If you want breech plugs and barrels made the way Dan shows on the bottom pic contact Hugh Toenjes. I have an 11" .53 with this kind of plug designed and built that way.

[jafo20]

Thanks.....if I place the liner opening just in front of the breech plug the the threaded liner hole hole will contact the barrel breech threads a bit....thats ok right?  Also is removing the breech plug before you drill the liner hole standard procedure?

thanks

[t.caster]

I also prefer the liner in front of the breech plug. If you get into the plug, then you may have to remove the liner before you can get the plug out. I only take the liner out when it is time to replace it, and they should last for a few years depending on how much shooting you do.
Precarved kitguns dictate the location of your touch hole if your lock is pre-inlet. No choice but to put it inline with your pan.

[Meteorman]

Many position the vent liner so the rear edge of the threaded vent hole will be just in front of the breech plug face.   
i.e if its a 1/4" liner, the hole is centered at (1/4"/2)+1/32" = 5/32" forward of the breech plug face.  This of course is determined when locating your lock plate, on a given breech plug face.
Most do remove breech plug prior to drilling vent hole. 
If the drillbit intercepts the breech plug face, it will deviate and create an oval hole.
/m

[Dphariss]

The breech plug needs to be significantly larger than the bore, the vent liner is seated AGAINST a shoulder. This cannot be done with a liner like a WL the walls are too thin. This is the result of the large counterbore. These need to be set forward of the breech face. I make my own liners to fit the  specific application.

Dan

[Dphariss]

If you seat the vent liner on a shoulder that is partly on the breech you CANNOT fit the liner unless the breech is in place. The breech is then locked in place by the liner.

Dan