In 1921, Charles Askins wrote in The American Shotgun
"It remained for America to have the final word in bolting mechanisms. Lug bolts located on or as part of the barrels were in the wrong place. The hinge-joint of the barrels acts as a fulcrum of a lever, upon which, the barrels rest and pry at the bolts. It takes three times as much strength in bolts, to withstand the pressure if they are placed an inch from the joint, as it would should the fastening be accomplished three inches further away.
Alex Brown moved his locking bolts from the lug and placed them in the extension rib, which is undoubtedly the right position for them mechanically. Throughout the world no other locking devise should be used on a shotgun save the rotary bolt."



The whole world had not taken Askins’ advice at that point in time, but some form of primary or secondary top fastening system was used by Westley Richards, Greener, Rigby, and Beesley in England, Merkel and most German-Austrian makers, the Manufrance Ideal, and in the U.S. by L.C. Smith, D.M Lefever, William Baker designed Ithaca and later models, Baker and Hollenbeck designed Baker Gun & Forging guns, Remington 1893 and 1894, and A.H. Fox.







William Wellington Greener in The Gun and Its Development 1907 provides an historical perspective on bolting mechanisms.
Page 145 "The Westley Richards' Breech-Loader"
"This gun is one of the first, if not the first, of the top breech-bolt mechanisms, and was patented in 1862. In addition to the lump underneath the barrels, upon which they turn, here is a lump projecting from the breech ends at the top of the barrels. This lump is of dovetail shape and has a hook; the projection fits into a correspondingly shaped slot in the top of the standing breech, and is secured there by a holding-down bolt sliding to and fro in the line of the barrels.
This bolt is pushed forward by a spring behind it, and is withdrawn by pressing the lever lying between the hammers to the right. The object of this particular arrangement is to prevent the standing breech from springing back at the moment of firing, and was undoubtedly a step in the right direction.
In 1865 the author invented a top cross-bolt, which passed through an extension of the top rib, thus wedging the barrels to the standing breech."

Chapter 15 of Shotgun Technicana by Michael McIntosh and David Trevallion discusses "Top Fasteners" specifically the Alexander Brown patent, and the almost identical Ansley Fox patent.
"The most basic principle in fastening any hinge is that the farther the fastener is from the hinge itself, the greater the mechanical advantage. That’s why door latches are placed where they are. In a gun, the action bar and breech face form two sides of a right triangle, so that the top or the breech face is farther from the hinge pin, in straight-line distance, than the bottom. In a side-by-side gun
there’s an additional advantage in that a top fastener is a bit more efficient in overcoming the effects of barrel flip-for the gun, if not for the shooter. With a top fastener, the barrels still flip downward on firing, but the action bar flexes less, and the fastener keeps the top of the barrels from pulling away from the breech face."
"The most interesting of the American top fasteners is the L.C. Smith’s patented by Alexander Brown in 1883. Where all the others used either Greener’s transverse bolt, some sort of flat bolt or hook on the front end of the top lever, or both, Brown designed his bolt as a steel cylinder that turns on a horizontal axis. A slot filed into the cylinder forms the actual hook, which fits into a slot in the rib
extension. The cylinder also engages a lip at the rear of the extension as a secondary bite. L.C. Smith described this arrangement as a double cross-bolt, although double rotary bolt would be more accurate."
They also discussed some disadvantages of the rotary bolt, with examples of actions shot loose with time (and magnum loads), but did agree that "...the top fastener mechanism…makes excellent sense."

Fox HE

What makes a rotary bolt better than, for instance, a Greener cross bolt?

All this rhetoric is fine, except that thousands of heavily used guns without rotary or Greener bolts are still going strong and are still tight. Parkers, Model 21 Winchesters, and Purdeys are examples. Mr. Greener seems to imply that there is a second locking bolt on a Westley Richards in the 1862 patent. There is not a second bolt, only the bolt that extends into the extension rib. I'm sure he was aware of that.

Thanks Dr. Drew! A timely article (certainly for me these days). The rotary bolt seems to be almost exclusively an American application. Smith, Baker, Fox, and Ithaca employed them endlessly and as the years pass, they keep on doing the job. Alex Brown's 1883 design is good one and in a mostly machine-made gun, they are hard to argue with. The Brits don't use them on anything "bespoke" (unless you consider the Greener cross-bolt or a 3rd-bite a variant) because they generally criticize any rib extension as another "unnecessary-encumbrance" to accessing the barrels for the loading process, and for London "Best" guns "they simply won't do". Allright...very different economic situations(!) and the Brits clearly know their market well (and make sure to build accordingly). With only a few exceptions, American guns have always tended more towards the unadorned "general-use" category anyway (historically, most American families could only afford one shotgun & it had to do it all, i.e. hunting & defense). If there was the luxury of another weapon at home, it was likely a rifle (or occasionally, a pistol) and similarly unadorned.

It was and is a purely economic game and that really is "the final word". Col. Askins was simply schilling for the home team (because "he knew where his bread was buttered"- to quote my maternal grandmother).

Stevens also used the rotary bolt on their early doubles.

All right, from a mechanical point of view a properly fitted, and I stress properly fitted Brown rotary bolt is attractive. Simply this. It holds the barrels down towards the frame while holding the barrels back against the breach. Self adjusts for wear and is a very simple mechanism. Double underlugs hold the barrels to the frame nicely. The holding to the breach is a function of the fore end I think. A cross bolt would work much the same as the rotary bolt. Needs a lot more fitting than the Brown patent. A double underlug with crossbolt such as a Merkel SXS is just overkill. either method would be more than fine. Lots of low enders work just great with a inclined slot on the barrel extension, lots of them.

In practice all work just fine. Clean the pin, lube the pin, shoot the gun!

Chief

Drew, please explain the picture of the HE Fox. It appears that the extension rib is broken. Am I mistaken or is that really the case? If so, how did that happen?

I believe Damascus has a hammer Purdey that he has owned most of his life, that has no extension and but a single locking lug on the barrel.

There does not seem to be an issue with it holding the gun closed. Properly fitted, they all do that, and a rotary bolt was no better and no worse than any other bolt.

Best,
Ted

David Trevallion sent me that, and this, pic long ago



A 2 3/4" chamber HE was used extensively with 3" 1 3/8 oz. at 1295 fps Super-X 'Record' shells.

Ouch!

I certainly don't think Merkels or Greeners with three locking mechanisms are over built.

Overkill, Brent. Not overbuilt. Overkill as in unnecessary, belt and suspenders. From an engineering standpoint either method would be adequate on its own. As stated, most low enders only have a rib extension with the inclined slot. I've never seen one fly open!

I disagree. Drew just showed us an example.

Disagree if you like. I imagine there is a lot more story to that broken rib extension than the obvious. By the way the Merkle could suffer similar damage, a rib extension is a rib extension.

I would ask, had the Merkle only had one locking system or the other would you have not bought it? Several other criteria that I look at first. Configuration, fit, condition, weight, balance etc. Would I buy a Merkle, sure! Seek one out solely because of its locking scheme, no.

Chief

No I would not have bought it.I would definitely not have bought it, had it only one locking lug or mechanism.

Westley Richards relied on the top extension alone in their early hammer breech-loaders as well as the first Anson and Deeley actions (seen here in an Edwinson Green c.1880).

As I understand it, when a double under bolt is properly fitted the entire load (in the absence of excessive action flexing or some failure) is taken by the rear bite the front bite acting as a reserve.

Add a top extension and whether the load is taken by the rear bottom bolt and/or the top extension is a matter of how well fitted each bolt is.

Thanks Parabola for showing a certainly not low end gun with the inclined slot/doll's head rib extension. For Brent's edification has it ever popped open on firing?

And Brent, I don't believe that, you twist! I believe the Merkle has double underlugs and crossbolt? Not one lug and crossbolt? I remember you have or have had in your estimation a soulless, ugly Ithaca/SKB. Double underlug, rarely single underlug. Still get it out for Grouse?

Chief

You said one locking system. I took that to mean one locking lug. Regardless, I would not shoothe ammo that?I run through my miracle in a two Underlog action.

No the s k b does not go grouse hunting or really much of anything else. I sure as hell would not want to hunt turkeys with it although others might.
My apologies for the strange verbiage.This voice to text it's not very effective and I don't have time to fix it

Whew! Happy you explained the voice texting! Thought you'd stripped a gear!

I refer you to page one, Eightbore's post RE double underlugs. He is spot on. I don't think a Win. 21 would balk at about whatever you could fire in it!

Chief

Actually, my grouse gun has only 2 under logs.It is a kimball skimmin and wood british gun. But it shoots only 7/8 oz loads at under sixty five hundred psi.

Lower grade Merkels do not have underlug locking. They are only held closed by the extensions. And, yes, people buy them.

Really?

It would be hard to get much lower grade than my model.8 in that lovely picture down below that Fuse and Ted hate so much. It has two under lugs and a cross bolt.

You will have to remind me where I said I hated your picture.

I feel sorry for your dogs, and your neighbors, but, that is totally different.


Best,
Ted

So why all the sorrow? Dusty is having a grand time in the snow right now.

I hadn't thought about the 200 & 300 series Merkels until they were mentioned, but the whole 200-204 series only have the Kersten crossbolt with no Purdey underbolting, whereas the 300-304 series have both underbolting and crossbolt.The 203E & 204E are considered pretty high grade guns. This thread also reminded me of a Churchill Premiere XXV 12 two-barrel set I have that has the Smith easy opening action with no top fastener and only a single bite on the rear underlug, and it was built in 1961.It's London proofed for 2 3/4" loads and weighs in at 6lbs. If it passed 2 3/4" proof with one lug, it's good enough for me. Regards, Sandlapper

This idea that you can't have too many locking mechanisms probably stems from when the Nutty Professor blew up his Rock Island built Springfield Model of 1903 rifle with an apparent careless handload.

He probably should get checked for remaining shrapnel embedded in his skull, which might explain irrational thoughts about anthropogenic climate change, an affinity for anti-gun Democrats, and this paranoid idea that Ted and Lefusil hate his tagline photo.

Just to add detail to Mr Hause's post, the first Westley Richards top rib extension bolt, his 'Doll's head,' was indeed patented in 1862 (patent No. 2506 of 1862), but it had a pull-lever, not the swing-lever described by Greener. Westley Richards' swing-lever patent was in 1864 (patent No. 2623 of 1864). Both use only the top extension as the locking lug, there are no bolts engaging the lumps under the barrels, which only serve to hook with the hinge pins.

Here is the 1862 pull-lever version:



And here is the 1864 lateral-lever version:

Interesting that the 1864 seems to have the evolutionary vestiges of percussion lock drip bars.

I am not sure what point is being made in this thread. That low grade Merkels and very early Richards have no under lugs - is the consensus that these guns are as good as high grade guns with three locking points? I usually do not look to the lowest quality guns to set benchmarks for anything like what is the best set of features. I know Greener was a real pro at marketing his guns. On the other hand, I do not think he made his crossbolt 3rd fastener as simply a marketing ploy. It is even more doubtful that all the Germans and other British makers that have copied that crossbolt (and presumably paid handsome patent royalties for the privilege) invested all of that expense and time in labor and licenses imply for as a marketing ploy. No doubt there are many great guns without 3rd fasteners, but I see no reason to believe that makes the third fastener superfluous either.

The single attachment of the Westley Richards guns was sufficient for the black powder loads of the day, even under substantial use, and Westley Richards' highest-grade guns did not have extra locking points. But I expect double and triple locking systems to be stronger and therefore, in greater demand by a shooting public rather obsessed with the strength of breechloader actions. Most early actions had a single attachment point, wherever it was. It looks like by the time gun actions were heading towards a kind of standardization dictated by market forces, double and triple systems were the norm.

I think that at one time Winchester removed the bolting from an M21 and proceeded to fire multiple loads through the gun, successfully. I wouldn't swear to this but I can't imagine that I would cook that up on my own! Maybe some one here knows?

To Steve Nash' point. A LeFevre Nitro or any 311 variant with their rib extension/inclined slot lock up will stand up well to just about any reasonable abuse one might offer. Guns made in somewhat recent times, built to a price point.

Chief

I disagree that the added locking points have anything to do with necessity and that added locking points were added because one locking point was not sufficient. Many examples of single locking points that are sufficient have been shown.

If they are unnecessary, and clearly not cheap to produce, why are they there?

Literally millions of shotguns are safe and secure, and have digested billions of shells with single locking bolt systems. That should be enough for anyone capable of rational thought. Multiple locking bolts on shotguns are there because, as P.T. Barnum famously observed...



P.T. Barnum is long gone, but he has been replaced by other Hucksters and Show Men...

As far as I know Merkle is the only newly made gun with a crossbolt. The crossbolt surely doesn't hurt, that is what Merkle is tooled up for so that is what they make. Why change now? Why do they have bolsters on their shotguns? No real need for them either. Why table lumps, (I think)? Monoblock is better, chopper lumps impress as well. I'm not dissing your Merkle, as I stated I would have one. I prefer upper end Japanese shotguns and some low end ones too! Oh and occasionally a "Woolnerized" 1100 20 Ga. classless pragmatist I!

Chief