this topic recently came up in another thread...

in my experience, i have only had this happen once...

it was a sleeved 16 ga english boxlock, made by one horatio jones, who was a small gunmaker, located south of liverpool...

anyway, the action included double under lugs and a third hidden fastener...

sent the gun to a well qualified smith, who rebuilt the bolting system, and all was well...

care to share your experiences here?

Mirikou over under... customer considered it "hard used" bought it in for missfires on the second barrel but we soon worked out it had had about 20 thousand cartridges through it... so i wouldn't have said hard used.


It didnt pop open on firing but the auto safety was linked to the underbolt... after a lot of mucking around trying to work out what was going on slow mo footage showed the underbolt was moving backwards a short way at speed enough to give the auto safety enough power to push the safety back... all springs were in good order and the gun was in otherwise good condition.

guns popping open really shouldn't be all that common. I would suggest that such an issue would be caused by lumps being knocked about and underbolts being refitted to damaged lumps. Any idiot with a hammer can make a gun "like a new one".. but it takes much more skill and work to make a gun "as good as a new one" and far more to do the work with subtlety

A brand new single shot Turkish 12 gauge, cannot remember the make, opened on nearly every shot. It was one of those folding actions with one coil spring activating both the underbolt and the trigger. Had my local spring man make a stiffer spring to the same external dimensions of the factory one. Problem cured.

I reckon that when the gun stopped against the shoulder on recoil, the inertia of the long underbolt lever, the one that hangs under the gun, was enough to compress the coil spring and retract the underbolt.

There are some older YT slow motion videos showing the effects of inertia on external shotgun parts, ie the oscillations of the opening lever on a Citori, the oscillations of the hammers on a muzzle loading SXS. It seems logical that if inertia can cause the top lever to oscillate left to right, it can cause the locking bolt to move back too. And if the movement is long enough the barrels are unlocked.

It would seem that the inertia driven moves happen after the shot has left the muzzle, so it is not such a major safety issue, but still, it is worrying. It should not happen.

I am not saying that the inertia of internal parts is the only cause, but it is a big factor.

This thread is the first time that I have heard of this. I cannot imagine how it can happen with a well made gun in good condition.

Guns opening on firing is a rare thing. Safeties being set on recoil is more common in my experience. Inertia is a powerful force. A good design takes it into account and deals with the mass of internal parts and their behavior under inertia.

Happened to me with an Ithaca Classic Doubles 20ga when I shot a couple Kent Fast Steel shells. (Late 471xxx SN gun.) Also happened, IIRC, with the early Ithaca NID 10ga magnums, when they were testing John Olin's new magnum loads.

Not rare in my experience. Its amazing how many Browning O/U sporting clays guns I've seen doing it, repeatedly. It seems a rubber band stretched around the grip, and hooked on each end to the tail of the top lever works pretty good until it's been rebolted. I can count 6 in recent memory.

There are certain wear-and-tear items on any gun. Browning's (and I assume other O/U and SxS guns) have latch springs that can get weak. The first time my Citori shot open, I order several latch springs. I replaced the one in the gun and have the others in a gun safe for the next time...it's the blue-ish spring in the top right of this photo...

Same for a Beretta SP2 I once had. It popped open until I replaced the Top Lever spring. The replacement was noticably "beefier" than the original.

I've had to fix a nice AyA #2 that needed to get a new top lever spring. The gun wasn't popping open yet but the safety was resetting because it had an automatic safety and the bolt was moving enough to reset the safety. In Elmer Keith's shotgun book he said it was not uncommon for Ithaca and Fox guns to pop open. He had a special order Ithaca they never got right.

Rotary bolt guns can open on firing if the contact between the bolt and the rib extension isn’t in the correct spot.

That’s exactly what’s wrong with my Sterlingworth Pin gun. Otherwise the gun is in very good shape. I just bought it a couple years ago from a reputable member and am very happy with it except the popping open issue. It was driving my local gunsmith nuts as he kept adding stronger and stronger lever springs which worked a little.

I finally talked to Jason at Pumpkin Mountain who explained to me how critical that rotary bolt-rib extension contact angle was.

would it be safe to say that a gun equipped with a visible greener type cross bolt is the least likely to pop open...

http://www.hallowellco.com/greener_crossbolt.htm

Wrong, ed:




Best,
Ted

Not a double, but impressive lock-up Lindner Daly "Sextuple" SBT

doc drew, once saw a german or austrian doublegun with that type of double locking system...its called a kersten

here it is...

http://www.hallowellco.com/double_kersten_locks.htm

ted...dim are ah pair o ugly frenchie gons...reminds one o dim citron cars...

here is the one once driven by inspector cluso...

https://www.tradeclassics.com/the-citroen-ds-a-top-ten-classic-car-contender/

Not a crossbolt ed. 2 bolts extend from the standing breech, similar to the bolting system for the Knick SBT

Ted, do you know why you should never wrestle a pig? You'll just get mud all over you, and the pig enjoys it.

stan, it is sad that you are so miserable...

read this and hopefully it will cheer you up...

https://www.foxnews.com/lifestyle/meaning-christmas-joy-faith-reach-others

doc drew, that looks interesting...

makes one wonder if anyone ever used a similar bolting system on a doublegon?