doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Any real advantage for "full hook" joint?

I usually hear that the full hook joint of Browning O/U shotguns is stronger than the bifurcated lumps design used in many other shotguns.

In real life though, would you say there is an advantage in longevity to the Browning system? Meaning do guns built with a full hook take longer to go off-face?

Assume we are comparing well built guns, such as a Citori to a Beretta 686.

Thanks.

I would say no.

There might be a small difference in bearing surface area, but with modern steels and good lubricants the designs should be equivalent for longevity.

I have both a 682 trap gun and a BT-99 with maybe 50k per each and I don't expect either to go off face in my lifetime. The Beretta is going to need locking pins at some point, but the next guy can take care of that in 30 years or so.

We have to remember that in a well engineered gun the hook or bifurcated discs are only acting as hinge pins . The Draws control the recoil loads and general wear and tear .
Ceasar Guerini seem to have had a good look at all the wear issues and possibly come up with a sensible solution , time will tell if they have solved a four century issue.

Draws??

The theory is that surfaces other than the hook joint absorb the forces and thus relieve the hook. Such a surface is the front side of the rear lump which is "fitted on the circle" and abuts against the action bridge, thus receiving the forces that arise on firing.

Two points there. When a larger hinge pin is fitted due to wear the barrels are moved back enough to eliminate any contact between rear lump and action bridge. There is no longer any "fitting on the circle" yest such repairs last a long time without developing looseness.

Second point is that folding type shotguns, as well as some less expensive non folders, such as the Midland Gamekeeper, have no central action bridge. In other words the cross pin bears the total force of firing, yet such designs seem to last a long time without loosening.

I suspect that the pheonomena that develop during firing are more complex than commonly protrayed. The dynamics involve more than simple rear thrust of the barrels and flexing of the action bar. There is, among others, the Poisson effect of axial contraction and radial expansion of the chamber ends of barrels (thick wall cylinders) during firing.

As to to the original post, the solid cross pin has not proven more durable than bifurcated pins in guns of equal quality, compare Superposed with Perazzi for a comparison.

The other intriguing fact is how autos and pumps never develop action looseness. Makes you wonder why.

Absolutely fantastic answers here. Thank you chaps!

Salopian and Shotgunlover are right. The draws take the force -- when properly fitted.. They're on either side of the inside of the action and they mate with corresponding parts on the bbl lumps.

You can see the draws on a Boss and then on Woodward in these pics:

Since the barrel breech "Should have been fitted tightly against the standing breech when built if the hing pin is enlarged "Only Enough" to compensate for wear in the hook it should not affect the draw. If after replacing the hinge pin the draw does not make contact then either 1; it never had it to begin with (Not properly fitted when new); 2- the pin has been made too big & barrels are not seating properly or 3- the frame has stretched.

Over the years I have observed dozens of SXS being retightened. In every case the barrels had to be smoked in to achieve a tight fit to the breech face. Smoked in means that the barrels were set back enough to require this operation. That seems to involve some rearward displacement of the barrels and I would think enough to eliminate draw contact between the rear lump and the bridge.

Some makers foresaw this problem and made provision for it. Blaser, Verney Carron, high grade Baikal OUs, Parkers, and maybe a few others, have replaceable "shoes" that can be changed to maintain contact. The idea is so simple that one wonders how it escaped the "best" makers.

Conceivably such a set up can be retrofitted to any SXS and make it infinitely repairable. It was fitted to my exprimental 3D printed prototype and it made fitting a piece of cake as it rendered the process a linear, one-surface-at-a-time business.

The replaceable Shoe on a Parker is to compensate for bolt wear. The bolt holds the gun closed, this has nothing to do with the fit of the barrel breeches to the standing breech. well yes, admittedly if the bolt is so loose it doesn't fully close the barrels will be loose to the standing breech, but by merely pulling them down by hand if there is no wear to the hinge they will be tight.

I have an H grade Lefever parts gun. This gun was "Rode Hard & Put Away Wet" so to speak. Top lever is well left of center with just a small amount of take-up left. Amazing thing is the ball hinge screw can be completely removed & the barrels bolt up to the same position, tight to the breech with no discernible difference in the position of the top lever. This is of course accomplished by the shoulders on the Doll's Head. The ball joint can be adjusted back to its proper position without causing the shoulders of the doll's head to lose contact.

It is also noted I have in my meager collection two doubles which have absolutely no built in wear compensation. One is a pre 1900 J P Clabrough, the other a circa 1902 J P Sauer & Sons / VL&D Knockabout. Both have double underbolts & a doll's head. Bolts & notches in the under lugs are parallel on both with top levers always stopping at center. Both are still tight & on face. This has somewhat caused me to wonder if tapered compensating bolts do not cause more wear due to the friction from their wedging action than they compensate for.