AmericanLongRifles Forums
General discussion => Gun Building => Topic started by: Daniel on March 03, 2015, 06:00:47 AM
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How tight are breech plugs to be ? I have one that is up to the shoulder on the out side and inside
of the barrel. Matches up to the flats top and bottom. I pulled it to check a possible problem inside,
but it was an optical illusion. The plug was tight , but didn't have to crank on it.
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Kinda of hard to describe just how tight the plug should be when fully indexed but, here is a try. When you finally snug a plug up to the perfect 12 o'clock position, it should go in with only "firm" pressure. You shouldn't have to pull on it like t a weight lifter to get it into position. Dong this will gall out the threads and create a loose fit. You don't want it so loose that finger tightening gets you to within one flat of 12 o'clock and you only have to lightly tug it into position with slight pressure. When everything is done right, the shoulders of the plug mate up with no gaps to the squared off breech of the barrel and the face of the plug mates up snugly with the shoulder inside of the barrel at the bottom of the threaded portion of the breech. Hope this helps!
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Thank you ! Helps a lot. I was a heavy mechanic for years so I know not to over tighten.
Just wanted to make sure. Everything lines up good. I blackened the face of the plug to
make sure it shouldered up correctly and it did.
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My old mechanic friend used to tell me "Tight's tight, too tight's broke".
I snug the plug with a 12" wrench, with an estimated 20 or 30 lbs pressure, and that's it. I could turn it past the mark if I crank hard enough.
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I use exactly the same indicator as Tom. We used to joke about it, saying: " wind it in 'til it goes soft, and then back it off a quarter turn". That's supposed to be a JOKE! Obviously not a gunsmithing policy.
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No matter what the plug will not unscrew under pressure. Tight enough to seal. that's it. I sometimes put pipe thread sealer on mine.
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20-30 lbs is good . I have about 25 on it with thread compound. It's always easier to remove with that stuff on
a plug , bolt or 2"x 60" cold rolled pin in a dump bed trailer. Big hammer too.
Daniel