My Barrel Suddenly Unthreaded

[Peter Laidler]

JM............ I'm absolutely staggered at what I'm seeing........... Is this common practice? Is it definately a factory bubba? Not that I disbelieve you, but surely not? PLEASE tell me that it is the work of a saboteur in the factory quality control department or some backyard farmer getting the most dollars out of his old rifle........ Can I take it that Springfiend Inc isn't the Springfield Armoury/US Military arsenal - or is it?

Centre punching around the perhipery is worse than peening the whole edge over with a pein hammer. At least with a pein hammer you'll get an even ring of swage (albeit a bubba swage to me......) around the edge.

When you said that this practice was done at the factory, I was imagining some sort of tidy ball-rolling around the breeching up edge to give a constant amount of deflection of the steel but hammering it with a centre punch is in my own honest opinion, well......., the realm of bubba engineering.

But, having said that, we did use a ball rolling method to tighten up the threads of Bren Gun barrels. A special tool (similar in design to a pipe cutter in effect....) was fitted onto and over the interrupted thread and a hard steel ball was screwed down onto the raised thread and rolled up and down the thread. As it did so, it spread the raised thread which tightened up the barrel in the barrel locking nut. But having said that, it was only authorised for use on blank firing and DP barrels. But, by tacit agreement, it was used on live firing guns where two worn but still serviceable barrels were towards the end of their life and one had worked loose.

Maybe this last paragraph ought to be in the Bren thread. So, Bren fiends, if one of your barrels has a clear distinct rounded impression going down the interrupted thread, then that's the reason. But I never saw or heard of an underturned barrel being tightened up in this way. Unless you'd showed me the pics JM, I'd never have bvelieved it - quite staggered to the point of speechless

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[jmoore]

JM............ I'm absolutely staggered at what I'm seeing........... Is this common practice? Is it definately a factory bubba? Not that I disbelieve you, but surely not? PLEASE tell me that it is the work of a saboteur in the factory quality control department or some backyard farmer getting the most dollars out of his old rifle........ Can I take it that Springfiend Inc isn't the Springfield Armoury/US Military arsenal - or is it?

Centre punching around the perhipery is worse than peening the whole edge over with a pein hammer. At least with a pein hammer you'll get an even ring of swage (albeit a bubba swage to me......) around the edge.

It is indeed planished around the periphery, but not center punched. Just regular old lightly crowned and polished hammer face. And, yah, it's pretty common esp. on Springfield Inc (Not the former US Armory!) barrels of either GI OR civilian manufacture! I know I have some in the shop that will show it better, but that one was only a couple of feet away at the time. You want more photos?

It it weren't for the requirement of keeping the sights aligned and torque induced by bayoneting bad guys, there's really no reason for an ultra tight barrel. Benchrest shooters have been known to do swap barrel guns that rquire only a strap wrench to make barrel changes. We even used to make takedown bolt rifles that were positioned by nothing more than a spring loaded ball. And they were quite accurate!



The main downside to peening for a civilain is that it can be unsightly. Or some ham-fisted lout might miss and b***** up the threads.
There's no structural reason against it- unless he wants to do drive-by bayonetings or pry open crates.