doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com K-80 Action Locking Mechanism

This question is for the mechanical engineering types of the forum. I grew up shooting Krieghoff shotguns and never really thought twice about the lock up mechanism on these guns I guess because I never had one blow open on firing nor have I even heard of this happening. But it appears to me the only thing that keeps the action closed is the hood on top of the receiver which slides over a metal flange on either side of the barrel. This looks like an inherently weak mechanism as compared to say an English Double with its' 3 rd bite. Apparently, however, the Krieghoff action is anything but weak and rather quite strong. Any comments regarding this?

The angle of the locking surfaces is apparently not critical as long as it is not too steep. However, when rebuilding a Krieghoff, the original angle is maintained. Of course, there are many other gun locking mechanisms that rely on very small locking surfaces, or no locking surfaces in some cases of self loading weapons. I was at Krieghoff USA last week discussing this very subject with one of the gunsmiths. He was asked if there was a jig for a vertical mill that made sure that surface was done perfectly on rebuilds. The gunsmith said that no jig was used and gunsmiths used the eye to determine when full contact was reached on both sides through the use of a file. The Krieghoff I have shot the most is 44 years old and has never had the contact surface welded or adjusted. The top latch is usually not the wearing surface, the barrel contacts being the area welded and filed into contact. None of my old Krieghoffs show any sign of being close to needing a rebuild of the locking mechanism. Two of them were built in 1974 and the other was built in 1967. The 1967 gun has been in constant all around use since I have owned it, twenty years now. Before that, it was a trap gun.

Really? It looks like the strongest of the bunch to me.

Note the position of the trunions (pivot point) on the K-gun design and also the Italian actions.

There simply isn't much torque to resist on firing, compared to a tall action with a classic style hinge pin.

Beretta gets away with two little conical pins, and it works just fine.

The Krieghoff is certainly better bolted than 680 series Beretta, and the Beretta is more than adequate.

Ive heard of an instance where an 28ga tubeset split at the chamber blowing out both chambers and the top wedge on a K gun,and it was blamed on the tubeset being not fitted to that particular gun.Sounded like malarkey to me unless it was also an overloaded shell in the mix.I guess I had to be there to witness it.

Have a look at what Krieghoff copied

The tube set is advertised as strong enough to fire the shell without suport. Sounds like a very big shell.
bill

If you consider the distance from the trunion to the locking point, the K-80 is at least 30% longer than most guns, and the locking point is at the very top rear edge bringing strength to the point of greatest torque on firing. So the K-80 has a significantly longer lever to hold the action closed. Besides, I think it was Greener who fired a gun without any locking lugs, just holding it in the normal manner, to demonstrate the torque was minimal anyway.