GPR clean out plug

[Eric Krewson]

I put a patch box in my nephew's Lyman GPR and tried to clean the barrel which was a rusty sewer pipe. After multiple scrubbings with red scotch bright the barrel was still rough but shot fairly well.

When I cleaned the gun and used compressed air to blow out the drum I noticed the so called clean out hole was blowing air out of it like a vent, Is this normal for a GPR? The open hole is very small, about 1/16"

 

[Rifleman1776]

Doesn't sound normal to me. I would take out the screw and replace with a better fitting one sealed with Loctite then filed flush so it can't be messed with.

 

[Phil Coffins]

I’ve never noticed a leak on any Lyman at that screw. I never remove them except to plug the hole with a longer screw then peen and file flush.

 

[n.h.schmidt]

The screw that should be in there is missing or somebody drilled a hole in the screw. Either way you have to deal with it. I have a breach from a 50 cal GPR .I will check on the screw size. It should be 4mm. You can't leave it like this. You have a volcano shooting out the side with every shot.

 

[Rifleman1776]

You have a volcano shooting out the side with every shot.

Ain't they supposed to do that. My flintlock rifle does it everytime.

 

[ohio ramrod]

My target rifle had a loose fitting cleanout screw that leaked, so I silver soldered it in place over twenty years ago and have had no problems since.

 

[Eric Krewson]

Thanks Guys, I have shot a flint GPR before but never a percussion, I suspected this was an anomaly but wanted to check and be sure.

 

[Grenadier1758]

@Eric Krewson, the previous owner wanted to vent the drum much like Manton, Nock and other early builders of percussion lock guns did when they were changing from building flint lock guns to making percussion guns. They believed that a vent was necessary to relieve pressure at the breech when the charge fired. Not really necessary, but not really harmful other than annoying to the shooter receiving the blast from the vent.

 

[nhmoose]

Back of Dixie catalogs used to recommend venting the breech drill the drum or cleanout screw, I don't know if they still do.

They said it would give a place for the air to go so the flame could get to the charge. I have no idea why, but I would not drill mine.