breech plug question

[curly]

I have a 40 cal. G/M barrel that I made a mistake while measuring for a vent hole. I made the mistake of using the wrong (1/2") breechplug instead of the 5/8" long plug that was fitted for the barrel. The port was drilled and tapped before I had discovered the mistake. Once the correct plug was installed I had two threads showing in the vent. I had no choice but to cut a path to the vent. My question is, was this the right way to do this? I'm concerned about fowling problems, corosion in the threads, even though I sealed them with teflon tape, and clean my rifles very well using cold water and 120 lbs of air to make sure the vent is clear. I will cut the barrel off and and redo the entire breech if this isn't kosher. Need your pro opinion guys.
Thanks
Curly

[JCurtiss]

If a 1/2" plug is the right plug relative to the position of the touch hole and everything else, why don't you cut off 1/8" form your 5/8" plug?

[longcruise]

If a 1/2" plug is the right plug relative to the position of the touch hole and everything else, why don't you cut off 1/8" form your 5/8" plug?

Wouldn't that just put him right where he is now?

Going to leave the answer to the primary question to better qualified members,   of which we have many.

[L Moler]

If it were me, I would install the 5/8 plug and drill back into it to the depth of the touch-hole (somewhat like a patent breech.)  I have a buddy in Spokane who does this on all of his guns. 

[JCurtiss]

If a 1/2" plug is the right plug relative to the position of the touch hole and everything else, why don't you cut off 1/8" form your 5/8" plug?

Wouldn't that just put him right where he is now?

Going to leave the answer to the primary question to better qualified members,   of which we have many.

Not the way I interpreted the problem.

It's my understanding that the touch hole was located and drilled in the barrel to be tangent to the face of a 1/2" plug. But instead a 5/8" plug was installed, causing the hole to run smack dab into the side of the plug. So if you cut off 1/8" from the plug, the hole should just clear the plug face.

[smylee grouch]

If I read this right, cutting off 1/8 inch from plug would leave 1/8 inch of threaded barrel in the bottom. I don't think this would be the right thing to do. Maybe I am reading it wrong but I would want the plug to butt up against a shoulder in the bottom of the barrel.

[David R. Pennington]

I agree with Smylee, I would want the plug to seat against the shoulder at the back end of the rifling. I would rather vent through the plug than leave the plug short in the threads. I am working now on fitting one with marking blue to get a tight seal there. Mark and file and repeat endlessly.....so it seems. My .50 has the vent back of the plug face just enough so I had to file a notch in the face of the plug and it works well and seldom fouls.

[curly]

I'll try to explaine my problem a little better. I have a 5/8 deep breechplug hole in the barrel. When I measured for a touch hole using a 3/8 ram rod I made the mistake of using the wrong breechplug. This was a 1/2". that left a 1/8" gap between the bottom of the breechplug hole and the bottom of the 1/2" breechplug.I drilled for the vent hole. Now That left my hole right in the middle of my breechplug seat, where the breechplug and the barrel meet. So when I installed the correct 5/8 plug, I'm looking at almost two threads in the vent hole. I cut a channel in the bottom of the plug, leading to the touch hole. My question is. Is this the proper method of taking care of this problem?
Curly

[David Rase]

Curly,
I ran into the exact same problem a couple of years ago on a 12g Getz barrel for my matchlock.  In a lapse of good judgment, I did just as you did, I used a rod and located the face of the breech plug and then transferred that measurement to the outside of the barrel.  I then removed the breech plug, set the barrel up in my drill press and drilled a 1/16" hole for the touch hole.  I noticed during the drilling process that the drill broke through the barrel wall thickness sooner than I had anticipated.  I removed the barrel from my drill press and took a look.  My gut feeling was right.  I had drilled the hole into the female breech plug threads.  I then started measuring everything to figure out what went wrong.  To my surprise, I discovered that the breech plug threads were 1/2" long as they normally should of been but the female threads in the barrel were 5/8" deep leaving a 1/8" gap from the face of the breech plug to the start of the barrel bore. 

To fix this problem, I replaced the short breech plug with a plug that seated properly.  I then removed the plug and filed a cone shape Vee notch from the center of the breech plug diameter to the touch hole.  Not as good as having the touch hole in front of the face of the breech plug but a more than adequate fix.
David

[Long Ears]

My first Chambers kit I didn't set the barrel back and had to notch my breach plug. That was about 4 or 5 years ago. After reading all of the possible horror stories about how bad this could become I've pulled the breach plug several times to check for erosion of the threads. It is totally clean, I do use anti seize on the threads when I install it. I have shot a couple thousand rounds through it and always used real black powder. I also clean it well after every shoot. Make sure your liner doesn't protrude past the inside of your barrel. Just my experience for what it's worth. Bob

[kaintuck]

use some washers between the plug face and the barrel..............a spacer of sorts~~~

tomtom said it would work...........
marc

[curly]

Thanks a lot guys. Thats just the information I was looking for. No problems with thread corrosion down the road is what I was worried about.
Thanks again'

Curly