NEVER use smokeless powder in any Merwin & Hulbert revolver!

[orpington]

If you had asked me this a few days ago, before I began reading Gunsmithing Guns of the Old West, by David R Chicoine, 2001, I would have thought otherwise, with caution, of course! Generally, anything manufactured before around 1905-1910, I would use black powder in, anyway, BUT I would have thought that if there was any pre-1899 revolver in which smokeless powder might be tolerated above any other, I would have thought it to be the Merwin & Hulbert, with its extremely fine workmanship and tolerances unheard of even today. However, in this book, on page 21-22, the author writes the following, in his "On the never use smokeless list: "All the Merwin & Hulbert revolvers. These are especially fragile. We say especially because these designs all use minimal amounts of steel around the cartridge chambers and the fact that the steel used in these guns has shown itself to be of highly inferior quality." On page 166, in the Merwin & Hulbert section, he writes the following: "Any Merwin-Hulbert (sic) revolver, repeat...any Merwin-Hulbert (sic) revolver should only be fired with ammunition that uses black powder or a black powder substitute as a propellant."

For those of you out there who might (erroneously) believe this extremely high quality workmanship might allow for judicious use of smokeless powder in these fine revolvers.

I stick to black powder in anything from the 19th Century, but not everyone else does...

 

[GBExpat]

Thank you for the warning!

My kinda luck, I would find a nice M&H and then proceed to accidentally destroy it with Trailboss loads ...

... but now that won't happen.

 

[Driftwood Johnson]

I would have thought it to be the Merwin & Hulbert, with its extremely fine workmanship and tolerances unheard of even today.

Ah, the old myth about the fine workmanship and tolerances of Merwin Hulbert revolvers. This myth has arisen chiefly because there has only ever been one in depth book published about Merwin Hulbert revolvers, Art Phelps' book The Story of Merwin Hulbert & Co. Firearms. Here is the Phelps book next to a Merwin Hulbert Pocket Army, chambered for 44-40, made sometime between 1880 and 1883.





While there have been many books published about Colts, Smith and Wessons, Winchesters, and all the other great 19th Century firearms companies, Phelps had the bully pulpit pretty much to himself, so everything he wrote is taken as gospel. If you read Phelps' book, you will see how he claims over and over again how the MH design was superior to anything else made at the time, and he claims that only MH had the capability to make parts precisely enough to build their design.

Poppycock.

I can tell you for a fact there is absolutely nothing more precise about a Merwin Hulbert revolver than anything Smith and Wesson was producing at the same time. In fact, the reason Merwin Hulberts, were produced with such an odd ball design is because S&W held patents that prevented any other company from making a Top Break revolver in the 1870s and 1880s. So to come up with a revolver to compete with S&W, MH had to come up with an unusual new design.






If you take the side plate of a single action MH you will find the mechanism is virtually the same as a S&W Top Break.

Here is the mechanism of a Merwin Hulbert frontier model.








Here is the mechanism of a S&W Russian model.






S&W brought out their first Top Break revolver in 1870, while Merwin Hulbert did not produce their first revolver until 1876. So who was copying who?




And Phelps never bothers to mention the fact that although you could quickly empty a Merwin Hulbert by rotating the barrel and pulling the barrel and cylinder forward, you had to close the gun up and reload one cartridge at a time through a loading gate, not much different than a Colt. You cannot reload a MH while it is broken open.








S&W Top Breaks, on the other hand could be emptied by breaking the gun open, and then reloaded while the gun was still open. Much faster than reloading a Merwin Hulbert. This is a S&W New Model Number Three, chambered for 44 Russian.







Don't get me wrong, Merwin Hulberts are fascinating revolvers, I am lucky enough to own three of them. But I always get a bit annoyed when the myth about how incredibly precise they had to be comes up.

By the way, I do agree with the late Dave Chicoine regarding shooting Black Powder in old revolvers. Colt factory warrantied the Single Action Army for Smokeless powder in 1900. Nobody is quite sure when S&W gave Smokeless powder their blessing, I have a reprint of a S&W catalog from 1905 recommending against it. As far as I know, Merwin Hulberts were no longer produced after about 1898, and I would never shoot one of mine with Smokeless powder.

This Merwin used to belong to a friend of mine. He really can't remember now whether he blew it up with Black Powder or Smokeless powder, although I suspect it was Smokeless. I own this revolver now, it has a new, custom made cylinder and a new top strap was fashioned and welded on.

 

[Crawdad1]

As usual and as always, excellent information Mr. Johnson, excellent information.

 

[orpington]

Driftwood Johnson, that is an EXCELLENT commentary!

A few things...

1. FIRST, would you hesitate to even fire a black powder round in a Merwin & Hulbert revolver? It sounds like you have, and would continue to do so. However, your friend's revolver did rupture, but it is unknown if the rupture was caused by a black powder or smokeless round. Given the way it was written, I "think" you strongly suspect that the rupture was caused by a smokeless powder round and that black powder rounds in a Merwin & Hulbert revolver are probably always harmless. Please clarify.

2. I had reason to remove the sideplate from a Merwin & Hulbert pocket army revolver recently, as well as a sideplate from a Smith & Wesson first model DA revolver in .44-40. I noted the internal mechanisms of both seemed eerily similar. So it wasn't just me!

3. I did not realize that the reason why these revolvers came about was to be unique from Smith & Wesson for patent reasons. But it makes sense! Everyone else was trying to, at the time, avoid infringing upon Smith & Wesson's patents at the time. I simply believed the unique design evolved from a desire to be unique from a marketing standpoint: Unique and unconventional sells!

4. However, while both Smith & Wesson and Colt revolvers had excellent tolerances in the late 19th Century, Merwin & Hulbert tolerances were still more precise. They simply had to be with such a unique design. This sort of precision leads to the suction phenomenon associated with some Merwin & Hulbert revolvers.

5. I had read somewhere that ALL Merwin & Hulbert revolvers were produced between 1876 and 1891. Is this assertion incorrect?

 

[Jim K]

While I have no doubt that M-H was careful to avoid S&W patents, S&W being quite touchy in that area and prone to sue at the drop of a bowler, I always heard and read that the idea was to be able to extract fired cases while leaving unfired rounds in the chamber. That goal was achieved, though the mechanism is fairly complex and pretty slow. It also requires that the cases be a specific length, which is why there were cartridges specifically designated for M-H revolvers; other cartridges would fit and fire, but not achieve the selective extraction that was the M-H's main feature.

Joseph Merwin and William Hulbert were neither manufacturers nor inventors of the revolver. They were financiers and Manhattan sporting goods dealers who, with other dealers, owned a controlling interest in Hopkins and Allen, which actually made the guns. I don't recall the actual inventor(s) but perhaps someone else does.

In use, the M-H is a bit faster to reload than the Colt SAA, but much slower than the S&W if one is willing to just drop any unfired rounds. It is also common for spent cases to jam the mechanism, requiring that they be removed by hand.

As to the supposed high quality of workmanship, all H&A products were well made, even their cheapest revolver lines. IMHO, the M-H revolvers are a bit better made than Colts, but not as well made as the products of S&W.

The dates of production for M-H guns were c. 1876 to c. 1883. All original guns are classified under federal law as antiques. There was an attempt made at manufacturing a reproduction a few years ago, but nothing came of it. It was claimed that the guns were so precisely made that no modern machinery could match the required quality, which is absurd; the truth seems to be that (as often happens) the enthusiasm of the few was met by the apathy of the many.

Jim

 

[Driftwood Johnson]

1. FIRST, would you hesitate to even fire a black powder round in a Merwin & Hulbert revolver? It sounds like you have, and would continue to do so. However, your friend's revolver did rupture, but it is unknown if the rupture was caused by a black powder or smokeless round. Given the way it was written, I "think" you strongly suspect that the rupture was caused by a smokeless powder round and that black powder rounds in a Merwin & Hulbert revolver are probably always harmless. Please clarify.

My friend Bill blew up that revolver a number of years ago. When he first told me the story of him blowing it up, I recall he told me as he stared at the blown up revolver in his hands he had said something to the effect of 'I guess I shouldn't have shot it with Smokeless powder'. Bill is a bit older than me, and his memory is starting to fail. When I asked him about it more recently he seemed to think he blew it up with Black Powder. But I remember his earlier comment, about he shouldn't have shot it with Smokeless, so I believe he probably blew it up with a Smokeless cartridge.

Bill is a terrific gunsmith, the best I ever met. After he blew up that MH he made a new cylinder for it from scratch. He also made a new Top Strap to replace the one that had separated from the frame, and had it welded on. Then he laboriously fitted everything back together again. As if that wasn't enough, Bill had a second, very similar MH, and while he was at it he made a new cylinder for that one too.

A few years ago Bill was paring down his collection and I heard through the grapevine that he had some Merwins he was willing to sell. So I expressed interest, and he offered to sell me the pair for a terrific price, which I took him up on. They are Third Model Frontier Merwins. This model was made from 1883 until 1887. As Bill told me, these are not museum pieces, they have been heavily reworked. Notice how the joint around the side plates stands out like a sore thumb because they were heavily buffed before Bill had them renickeled. This was part of the reason he gave them to me for a terrific price, the other reason is he is a terrific guy.

The Merwin at the top of this photo is the one Bill blew up, the one at the bottom he did not blow up. If you look closely at the rear of the top strap of the top revolver, you will see joint to the frame is a bit less than perfect. For some reason Bill also built up the front sights on these revolvers, MH revolvers did not usually have such tall front sights. He probably did this because with the original front sights they tended to shoot high. The top one was originally chambered for 44-40, the bottom one 44 Russian. To keep things simple, Bill chambered both new cylinders for 44 Russian. The fact that they both have new cylinders made from modern steel means they are stronger than they were when they left the factory, and could probably be safely fired with Smokeless powder. However, I choose to only shoot them with 44 Russian cartridges loaded with Black Powder.





When we completed the deal, Bill threw in the blown up cylinder, since he had no use for it, and he knew I would appreciate it. You can see the rupture probably started at the locking notch, which has the thinnest cross section of steel in the cylinder. Only a few thousandths thick right there. Then the rupture split in two, separating a piece of the cylinder just about midway through the flutes. When that piece of the cylinder separated, it took the top strap with it. Very typical of blown up cylinders. None of the other cartridges in the cylinder fired. Even so, you can see the two chambers on either side of the blown up one were severely deformed by the over pressure event, they were severely folded right at the locking notches. I believe if there had been much more force in the over pressure event, those two chambers might have ruptured too.







The third MH I own is this 2nd Model Pocket Army that I bought about two years ago. You will notice there is no top strap, and the flutes are what are called Scoop Flutes. The story with Scoop Flutes is that although they were a bit more expensive to cut, they left a bit more steel around the chamber throats, and Joseph Merwin felt that made them stronger. Later models did away with the Scoop Flutes when stronger steel was available. According to Phelps, this model was made from about 1880 until 1883 when a top strap was added and the Scoop Flutes were done away with.

This Merwin Hulbert is chambered for 44-40. Bill did a bit of rework to this Merwin for me, the lockwork had some problems, and the chamber throats were very tight. Something like .424 in diameter if I recall correctly. These revolvers have five groove rifling, which makes it difficult to get an accurate reading on groove diameter. However shoving a .428 soft lead bullet through the barrel left good rifling marks engraved on the slug. Since there is no top strap on this revolver, I did not want to stress anything by raising pressure squeezing a .428 bullet through .424 chamber throats. As it is, the barrel/cylinder gap is a hefty .016 or so, undoubtedly because the barrel is only supported on the bottom, and Lord only knows what kind of ammo had been fired through it over the years. So Bill reamed the chamber throats to .429.



So the short answer to your question is I would hesitate to fire Black Powder rounds through a Merwin Hulbert revolver, with the original chamber throat dimensions. And unless I had thoroughly checked out the condition of the revolver. However with the opened up chamber throats, I do not hesitate to fire this one with Black Powder rounds. I would never fire Smokeless rounds through any Merwin Hulbert revolver, no matter how fine the condition was.

2. I had reason to remove the sideplate from a Merwin & Hulbert pocket army revolver recently, as well as a sideplate from a Smith & Wesson first model DA revolver in .44-40. I noted the internal mechanisms of both seemed eerily similar. So it wasn't just me!

Yup!

3. I did not realize that the reason why these revolvers came about was to be unique from Smith & Wesson for patent reasons. But it makes sense! Everyone else was trying to, at the time, avoid infringing upon Smith & Wesson's patents at the time. I simply believed the unique design evolved from a desire to be unique from a marketing standpoint: Unique and unconventional sells!

Smith and Wesson's ferocity in protecting their patents came about from Daniel Wesson's experiences as a young man working for his older brother Edwin, manufacturing precision target rifles. When Edwin died suddenly and unexpectedly, the courts ruled that all the assets of the company would go to Edwin's creditors, leaving Daniel high and dry. He lost everything, including his personal tools that he used in his daily work. He resolved then never to be taken advantage of again. And rightly so. If somebody has done the work to either patent something himself, or buy a patent, then that patent is his property and he is well within his rights to defend his patent.

4. However, while both Smith & Wesson and Colt revolvers had excellent tolerances in the late 19th Century, Merwin & Hulbert tolerances were still more precise. They simply had to be with such a unique design. This sort of precision leads to the suction phenomenon associated with some Merwin & Hulbert revolvers.

Again, poppycock. There was nothing particularly difficult about tolerancing a hole and a rod so that the fit was tight enough to create a bit of suction when one tried to separate them. As for the the 'precision' required to make such a 'unique design', take one apart some time. You will see there are plenty of places where the fit is quite sloppy. For instance the fit of the slot in the arbor where the barrel latch rides is not particulary precise. Plenty of slop in that fit.





The thing that most impresses most newcomers to the world of Merwin Hulberts is the very clever rotary cuts for the joining of the barrels to the frames. Yes, it is a very clever idea. But it was simply done with fixturing that would cut the joints in an arc around the center arbor of the revolver. Clever, not earth shaking. And certainly not outside what S&W could have done if they had a mind to. They simply did not have a mind to.

5. I had read somewhere that ALL Merwin & Hulbert revolvers were produced between 1876 and 1891. Is this assertion incorrect?

I'm not quite sure where I came up with that 1898 date. Phelps states that the First Frontier Model was made in 1876. The last manufacturing date he mentions is 1887 for the Fourth Model. He states this model was first cataloged in 1889.

I have a reproduction of the 1887 Merwin Hulbert catalog that is profusely illustrated with MH revolvers and ammunition, as well as rifles and shotguns.



The last catalog in Phelp's book is the 1890 John P Lovell Arms Co. catalog, showing an extensive array of Merwin Hulbert revolvers and ammunition.

So it appears to me that even though Joseph Merwin died in 1879, Merwin Hulbert revolvers were still being produced as late as 1890.

Beyond that I do not know.

 

[orpington]

Much Thanks, Driftwood!

Now that you mention it, the fit of the slot in the arbor is also somewhat sloppy in my Merwin & Hulbert revolvers. I did notice this, too, but the precision and tolerances with regards to these revolvers, or at least this being ingrained in my head (the Art Phelps book), well, I guess it made me simply look the other way.

Nonetheless, they remain a unique design, and a rather neat one at that! About a month or two ago, I loaded some black powder rounds, and almost took one of my Merwin & Hulbert revolvers to the range, but never made it to the range at all that day. I think I loaded these rounds with FFFg powder, which would create more pressure than FFg. Now, after what I am reading, fortunate that I did not fire this revolver at all! I will relegate these revolvers to being display pieces ONLY, and fire my Smith & Wesson and Colt revolvers instead.

 

[Driftwood Johnson]

Howdy Again

Not knowing what your revolvers were, their caliber or their condition, I cannot comment on the advisability of shooting them. However FFFg does not raise the pressure all that much over FFg, so if the revolvers are in sound condition they are probably fine to shoot.

Regarding the business about fired cases being extracted and unfired cartridges being retained, I have not found that to work out very well. Here is a photo of the 'retaining ring' around the arbor that serves as an extractor of sorts, retaining the rims of the cartridges when the barrel and cylinder are pulled forward. This photo is of one of my Frontier models. Yes the fit of the screws is sloppy, but that is because Bill had to rework them heavily to make them work, they did not leave the factory that sloppy.





Here is my 44-40 Pocket Army opened all the way. You will notice the rounds are being retained by their bullets. You will also notice that gravity has caused them to slip out of alignment with the chambers. What this means is that in order to close the gun again, some of the cartridges need to be manually shifted a little bit so the chambers can 'swallow' them again as the gun is closed. And even when dumping a full cylinder of empties out, I often have to flick one or two shells out of the gun that got caught on the arbor. No, I do not have a MH chambered for 44 Merwin Hulbert, my friend Bill has one, but since the ammunition is no longer available he used I believe cut down 41 magnum cases to make ammo. In any case, my 44-40 Pocket Army is designed specifically for 44-40 ammunition, the cylinder opens the correct amount to drop out spent cases and retain unfired rounds, and it still is a bit fussy to keep the unfired rounds in the gun.



Then on top of that, the gun must be closed again and fresh ammo must be loaded one at a time through the loading gate. The 'retaining ring' prevents fresh ammo from being loaded while the gun is open, the rims can only slip under the ring when they are loaded through the loading gate.



Yes, Smith and Wesson Top Breaks can have a tendency for the extractor to slam down and get under rims, that is why I always flick a Smith sideways as I open it so gravity and momentum will help eject the empties without them getting caught under the spring loaded extractor star. Here is a photo of the cylinder from my S&W New Model Number Three. If a spent round manages to slip under the extractor, I have to pull the extractor up and wiggle the offending round out from under the extractor. Yes, the extractor is digging into my thumb in this photo, yes, it is painful. Besides that, the gun is over 130 years old and I worry how much abuse the braze holding the extractor to the extractor rod will withstand.



I am fortunate to own three Merwins, five Number Three sized Smith and Wesson Top Breaks, plus several smaller S&W Top Break pocket pistols. I find that the mechanism of the Merwins is actually simpler than the Smiths, with fewer moving parts. And I am in complete agreement that the workmanship of a S&W Top Break is superior to a Merwin Hulbert, despite the myths about the legendary precision of the Merwin Hulbert. As I have said before on several gun boards, there is nothing that Merwin Hulbert was doing that S&W could not have done if they wanted to. They just didn't need to.

.........There was an attempt made at manufacturing a reproduction a few years ago, but nothing came of it. It was claimed that the guns were so precisely made that no modern machinery could match the required quality, which is absurd; the truth seems to be that (as often happens) the enthusiasm of the few was met by the apathy of the many.

Yup, complete baloney that modern equipment could not have duplicated the MH design. The reason the recent attempt to build a Merwin Hulbert again failed was they were underfunded. They got as far as producing some very impressive looking 3-D models in the computer, and made a few parts, but then it all came to nought.

But all of this myth busting still does not detract from the fun of owning and shooting a Merwin Hulbert.

 

[Jim K]

FWIW, I did fire a couple of cylinders of smokeless ammo from one of my .38 M&H revolvers and nothing blew up, but I think "don't" is good advice. On that failure, my "gut feeling" is that the cartridge was considerable higher pressure than a factory smokeless, probably a hot reload.

The fact that the chamber did not just split, but that it was blown open with such force that the metal of the adjacent chambers was "wrinkled" seems to speak of pressures well above the 17k psi or so of the SAAMI spec.

Jim

 

[Driftwood Johnson]

On that failure, my "gut feeling" is that the cartridge was considerable higher pressure than a factory smokeless, probably a hot reload.

My friend Bill would never have put a 'hot reload' in any antique revolver. Yes, the round was probably a reload, but it would not have been hot. He knows better than that.

 

[orpington]

My guess is that it was not hot, but simply a smokeless round. However, there still is a sliver of doubt, which is why you have convinced me to probably not even fire with a black powder round. I would really hate to destroy a 125 + year old revolver.

 

[AJumbo]

You know, there's always "that guy," and today I'll be him.

Could rounds loaded with full wadcutters, seated flush with the mouth of the case, be loaded in the MH while it's open? Would enough reload time be shaved off to make the extra extra time at the press worth it?

 

[Driftwood Johnson]

delete. Hit the reply button too soon.

 

[Driftwood Johnson]

You know, there's always "that guy," and today I'll be him.

Could rounds loaded with full wadcutters, seated flush with the mouth of the case, be loaded in the MH while it's open? Would enough reload time be shaved off to make the extra extra time at the press worth it?

No.

It is difficult to understand why this will not work without actually holding a Merwin Hulbert in your hands, but I will try to explain.

This is the 'extractor ring' that surrounds the arbor on a MH.

There is a relief all the way around the extractor ring, and the rims of the cartridges must slip under the ring into the relief.





This is the loading gate, in the open position. Notice that with the loading gate open, there is clear access to the relief under the extractor ring.





In this photo I am holding a cartridge in the loading gate, simulating the way it slides into a chamber in the cylinder. With the loading gate open, the rim of this cartridge bottoms under the relief under the extractor ring. As the cylinder is rotated to load the next cartridge, the rim of the round already in the chamber slides around the extractor ring, held captive between the extractor ring and the recoil shield. This process is repeated for as many rounds as you want to load.





The problem is not slipping wadcutter rounds into the chambers. Here I have slipped six empty brass shells, which pretty well simulate a wadcutter loaded flush to the case mouth. It was easy to drop six empty cases into the opened gun.

The problem is, they will all now bump into the extractor ring when the gun is closed. That is exactly what is happening here, the extractor ring interferes with the rims and the gun cannot be closed up completely. The rims have to slip under the extractor ring for the gun to be closed all the way.




Yes, you could load one wadcutter round, and one wadcutter round only the way you describe. I can take an empty case, and seat it under the extractor ring, then close the cylinder on it. But that requires holding the 'wadcutter round' in position with one hand while I close the cylinder on it. I do not have enough hands to do so with more than one round.

Trying to load rounds with a conventional bullet this way is completely impossible. Trust me, I have tried it many times. With a conventional bullet in the round, one cannot drop it in position parallel to the chamber, it has to enter at an angle. And the angle prevents the rim from slipping under the extractor ring. You have to hold one in your hand, but trust me, it simply cannot be done.

The only way to practically load a MH is one at a time through the loading gate.

 

[Tallball]

I always enjoy Driftwood's informative posts!

 

[orpington]

I always enjoy Driftwood's informative posts!

+1 (and +2, +3, +4, and +5!!!!!).

 

[orpington]

Driftwood (and others),

Obviously, I hesitate to fire my Merwin & Hulbert revolver with black powder due to what I have read, elsewhere and in this post. But what about loading a .44-40 round with ~25 grains FFg topped off with ~15 grains Cream of Wheat?

Mention of the condition of the Merwin & Hulbert was alluded to. Photographs to follow soon!

 

[orpington]

Here is my Merwin & Hulbert. Mechanically sound...

If anyone has a screw that will fit that missing screw in the sideplate, or knows of where to get one, please let me know,

 

[Driftwood Johnson]

Howdy

Yours is the same model as mine, a 2nd Model Pocket Army, chambered for 44-40, although your barrel is much shorter. Like mine, yours was probably made sometime between 1880 and 1883. After 1883, the 3rd Model came along, with a top strap. The marking on the left side of the frame, CALIBRE WINCHESTER 1873, is the way Merwin Hulbert marked the guns chambered for 44-40, since 44-40 was the most common chambering for the Winchester Model 1873 rifle.

My MH is in pretty good condition, everything locks up nice and tight. My reluctance to shoot it, even with Black Powder, was tied to the fact that the chamber throats were quite tight, only about .424. I was afraid the tight chambers might cause the pressure to increase. After I had the chamber throats reamed to .429 I was no longer reluctant to fire full house 44-40 loads with roughly 33.3 grains of Schuetzen FFg under a .428 200 grain soft lead bullet. That amount of powder will be compressed about 1/16" - 1/8" when the bullet is seated on it.

Adding some filler is probably a good idea, it will reduce the powder charge, and therefor the pressure generated. I do not know how much, but it will probably reduce the pressure somewhat.

Have you been able to get a measurement on the chamber throats? As I reported earlier, given the fact that these revolvers had an odd number of rifling grooves it is difficult to get an accurate measurement on the groove diameter, but when I slugged the barrel with a soft .428 bullet I got good engraving of the rifling on the bullet.

 

[Malamute]

Very cool guns, Ive always admired them.

I'm curious. On another forum, Kirk D and I believe someone else had some actual pressure tested smokeless information, and with the CORRECT powder, smokeless loads were lower pressure and the same slow pressure curve than black. I don't believe its entirely correct to lump all smokeless loads together, especially when the correct ones can be even easier on your gun than black.

 

[Driftwood Johnson]

Yes, you are probably correct. There is a poster on the S&W Forum who also poo-poos the idea of never shooting Smokeless powder in the old guns. I cannot remember the specific powder he uses, but he also says that there are Smokeless powders that will duplicate the Black Powder pressure curve as well as the Black Powder pressures.

My take is, Colt did not factory guarantee the Single Action Army for Smokeless Powder until 1900. When they did guarantee the SAA for Smokeless, it was probably with the bulk powders of the day, certainly not a fast, modern pistol powder. With S&W there is no hard line in the sand as to when they felt it was OK to use Smokeless powder in their revolvers. In the catalog of 1900, S&W recommends against using Smokeless powder in their revolvers, mostly because they felt the consistency of the powder could not be guaranteed, and they specifically would not guarantee their revolvers if fired with Smokeless powder. In the 1905/1906 catalog, S&W was still recommending against Smokeless powder and specifically said they would not guarantee their revolvers if they were fired with Smokeless powder.

I doubt if any of the old New England firearms manufacturers, Merwin Hulbert included, had access to steels that were any better than what Colt could get. For that reason, my rule of thumb is I will not shoot a pre 1900 revolver with anything but Black Powder. Sorry, I am not up to doing the research on slower burning Smokeless powders and do not want to use my guns as guinea pigs.

 

[Malamute]

Cant go wrong being careful with the old guns, they aren't easily replaceable.

 

[Gordon]

I bow to the wealth of knowledge about M&H revolvers here, but 30 or more years ago I fired more than one box of .38 S&W old factory smokeless loads thru my late manufactured M&H folding trigger .38 with no ill effects at all. I sold that gun , still in grat shape about 10 years ago for good money. I have a feeling the later .38 frame M&H revolvers were a little stronger , generally, than the large bore guns . I agree tho these days I would not consider anything other than black powder loads and even then now consider M&H revolvers beautiful relics to be admired not fired.

 

[orpington]

Have you been able to get a measurement on the chamber throats? As I reported earlier, given the fact that these revolvers had an odd number of rifling grooves it is difficult to get an accurate measurement on the groove diameter, but when I slugged the barrel with a soft .428 bullet I got good engraving of the rifling on the bullet.

I measured the chamber throat with a Lyman Dial Caliper and obtained a consistent measurement of .422. Now, I had never measured a chamber throat before, but reasoned since the measurement is precise to thousandths of an inch, and one has the flat end of the caliper against a round chamber, there could be some imprecision involved. So I searched for this on the internet and, ahaa (!), there is indeed an article that references this: http://www.grantcunningham.com/2006/08/measuring-chamber-throats-calipers-vs-pin-gages/

I do not have a pin gage, but it appears that Grant Cunningham's (one) measurement described identified a value of .356 with dial calipers and .3585 with the pin gage, a variation of .0025, which, unscientifically, sounds about reasonable. So, .422 + .0025 = .4245, slightly greater than the value of .424 you obtained prior to reaming, and significantly less than the .429 reading obtained after throat reaming.

So, pressures might be increased firing a .427 diameter bullet. If a .423 lead bullet could be obtained, +/- .001, perhaps this one could indeed be fired.