doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Underlever opening ergonomics

Don brings up a good point. Many gun owners don't understand the purpose of individual locking parts. The concept of "unloading" a certain part is lost on most gun owners, but tens of thousands of Beretta over unders in daily use have a device that, fitted correctly, unloads the trunnions.

I thought this gun, which is owned by my Son In Law, might be of interest. It is an unusual mechanism that didn't actually work very well, which I guess is the reason you don't see many of them. It was obviously an experimental or transitional mechanism before they had fully worked out the 'standard' hammerless mechanisms. It has an underleaver which pushes downwards to unlock the barrels and cock the hammers, rather like the martini henry rifle, but they hadn't got the mechanical advantage quite right. If you fire both barrels it is a real struggle to push the leaver down hard enough to cock both hammers. If you fire just one barrel it is fine, but both is a struggle. To aid cocking the hammers there are side cocking leavers which can be used as well. These leavers can also be used to 'de cock' the gun and make it safe. In the world moving from good old hammerguns, which could be rendered safe by lowering the hammers, to a world where every gun went around full cocked all the time this would have appealed to the safety conscious 'oldtimers'
The other interesting feature of this gun is the safety leaver - it works the opposite way round to the conventional ones. If you think about it it makes total sense to those used to hammer guns - you pull them back to activate the mechanism so why not pull back the safety to achieve the same result. My guess is that that like so many shooting variations which were possibly used to get round patent rules the rest of the manufacturers adopted the opposite direction - but that is only a guess.
As you would expect from me it is a Perrins of Worcester!!!

I have just found a couple more photos which may be a little clearer.

What an interesting gun...

Don;
Yes I had indeed missed that point if it is in fact true. As I said I have never owned a gun with this bolting system, burt as far as I knew it only pulled the barrels down against the frame. I had never heard this aspect mentioned before.
If it does serve this function it will of course require careful fitting or will be like many of the rotary top bolts & still serve only a single purpose.
If it is in fact fitted firm enough to unload the hinge then it is one of the few older actions which does so.
8-Bore;
Am I save in assuming on the Berettas you are speaking of the lugs on the sides of barrels which fit cutouts in the receiver side wall. I can definitely see how these could be fitted to unload the trunnions a bit.
I cannot say for certain the rear lump of a double underbolted gun has ever been fit to actually unload the hinge but if properly fitted with minimum clearance shoild certainly be a plus in resisting the bar from stretching.
Thanks for both for all the input. When I asked What makes it stronger, this was the sort of answers I was seeking. Just the fact it could clamp the barrels tightly to the bar didn't really impress me all that much. This other adds much more to think upon.

Miller, I took a look at my Woodward SXS DR from 1879 (450-400 2 3/8") which is the only Jones I have at this time. The "T" has made a shiny spot on the back of the back bolting slot. That indicates one gun as I described.Perhaps some of the gunmakers will weigh-in on this question.

As far as unloading the hinge pin/trunions goes, the answer is that "draws" are relatively common, but not universal. Vic Venters published an article on "Jointing and the Circle," and included it in his book, "Gun Craft," see page 11. This dealt with the fitting of the front edge of the back lump to the back edge of the "bridge" of the action body so as to "draw" barrels firmly onto face and the hook off the hinge pin. Purdey's (at least for one) currently makes SXS guns with replaceable draws and supplies a series of replacements each larger by a few thou to compensate for wear and restore on-face with a simple drift out drift in part.

The 1909 Boss Over/Under patent calls out an interacting dove tail joint of the action sidewall and barrel breech verticals that are fitted to draw the barrels onto face and unload the studs (trunions).

DDA

Interesting.

My take is that whatever tightly fitted system you might select, it will wear with the opening and closing action more than it ever will with firing stresses.

Build interference and wedge fit all you want, it's going to wear and 'shoot' loose although the actual 'shoot' part isn't causing it.

I'd bet that with any sound lockup system if you could close the thing once and somehow pressurize the vessel 100K times to simulate firing and associated stresses, you would measure no wear upon disassembly.

These things don't stretch apart, they grind themselves apart.

Thank you all for the interesting responses.

Bob Blair, that Mortimer is stunning. It offers the elegance of teh Dickson, and I suspect with a more robust action. Love the sweeping lines and the uncluttered receiver top. It also seems that the lack of a top lever would make the internals much simpler than a top lever gun.

Old farmer, that is an amazing double with the cocking indictors on each lock. Interesting observation about the cocking effort involved depending on the number of springs that have to be compressed, it reflects my experience with the French Ideal which is also a lever cocker.

KY John, I will look up Kirby Holt for sure.

Reason I posted the question is a semi finished action which is lying there wanting attention. That Mortimer is giving me ideas. Forging the underlever is daunting, on the other hand the end result, if it has the lines of that Mortimer, would be worth the trouble.

Don:
Thanks for the info. I have had a number of guns over the years but to the best of my knowledge none of them were fitted to actually draw the hook from the hingepin. Of course they weren't in the class of a purdey. One further question, strength wise which in your opinion adds the most; a properly fitted Jones, a properly fitted rear lump, or a properly fitted top bolt. From my limited perspective it does not really seem to be as desirable to actually unload the hinge, as much as to simply share its load. Any of these if properly fitted will do so.
Shotgunjones;
I will say I am in full agreement with this post.
Two guns which I presently have though are worthy of comment I think in this thread, though I have mentioned them before.
One is a lowly J P Clabrough, Birmingham proofed, the Other a KNock-About VL&D/J P Sauer. Both are double underbolted (No Draw) with Doll's Head. Neither has compensated bolts, Neither the bolt nor the bites in the lumps have any taper to them. Both are still tight & on face, though both are more than 100 years old. On both the rear surface of the front lump cams the bolt back in closing so the top lever is not latched open. In studying these actions it seems to me as the gun is closed, firmly but not forcibly, as the bolt clears it snaps home with virtually no friction, thus no wear.
Might it be that a tapered bolt while "Compensating" for wear in fact actually induces said Wear.

[quote=2-piper One further question, strength wise which in your opinion adds the most; a properly fitted Jones, a properly fitted rear lump, or a properly fitted top bolt. I'd be inclined to go with the circle draw fitted rear lump. However, there are so many other factors that this opinion would be very hard to back-up.

From my limited perspective it does not really seem to be as desirable to actually unload the hinge, as much as to simply share its load. Any of these if properly fitted will do so. If the hinge pin is properly/tightly jointed to the hook there will be no way to truly uunload it. So, you are both right and astute in your observation.
[/quote]

DDA