winchester model 12 combat, bayonet adapter flew off!

[brentn]

So we were shooting the model 12 at the shotgun range using regular #7 loads when I saw the heatshield/bayonet combo fly off the end of the barrel! The barrel has the grooves to hold the adapter in place, and we put it back on and tightened the adapter as best we could, but it started to come off and slide off the end of the barrel again with every shot! it was the weirdest thing, and I don't understand why its doing it. Even with the bayo/heatshild assembly off partially, it was still not possible to twist it off with the hands, or move it, but with every shot it inched more and more off the barrel.

Eventually we took off the bayonet/heatshield assembly but the magazine tube is now unsupported...

Any ideas as to why something like this happens?

 

[Virginian]

Because you didn't put Loctite on it. Blue threadlocker and/or 770 fit maker should solve the problem. Loctite makes all kinds of neat stuff; check it out. And no, I do not own any stock.

 

[Grunt]

I had the same problem with my Norinco 1897 Trench gun. No matter how tight I screwed down the screws, it would slide under recoil. I think it's somthing like trying to break loose a FAL receiver stub in that if you put steady pressure on the wrench (or in this case, try to move the heat shield with your bare hands) it won't budge. However, when you hit the breaker bar (or in this case the gun is fired) the jarring shock moves the wrench and is free to turn. My solution was to sprinkle some Brownells rosin between the barrel and het shield. Never had a bit of trouble after using that trick.