We’re not referring to those shotshells containing stainless (or not) steel shot, designed by environmentalists to embugger waterfowl and upland hunters.  We’re talking about shotshell cases that were made of stainless steel, to let owners safely fire modern black powder loads in ancient — even Damascus-barreled — breech-loading shotguns.

This 1878 Colt (now on Gun Broker) is an example of the kind of gun that could use these.

This 1878 Colt (which just now sold, or didn’t, on Gun Broker) is an example of the kind of gun that could use these.

They were once manufactured by a company in Yuba City, California (one suspects an offshoot of the then-beginning-to-struggle SoCal aerospace industry) named Conversion Arms, Inc., and promoted nationally. But since then, they’ve vanished without a trace.

Here’s what the late John T. Amber, for many years editor of Gun Digest, wrote about them in the 1979 annual:

Stainless steel shotshells

Modern smokeless powder shotgun cartridges are a no-no for old shotguns made long ago – the outside hammer guns, with or without Damascus (twist) barrels, even many early hammerless guns – and factory loads powered by black powder are hard to find, impossible to locate in many areas.

This Union Machine Co gun is Belgian proofed. It's in remarkable condition -- the bores on these old guns are often trashed by corrosive cartridges of the day.

This Alger Arms Co gun (not Union Machine as the picture filename says, our error) is Belgian proofed. It’s in remarkable condition — look at the case hardening, still visible! The bores on these old guns are often trashed by corrosive cartridges of the day. This one doesn’t appear to be — $825 starting bid on GB. This was the sort of gun the conversion cartridges were meant to save.

Now there’s a good solution – Conversion Arms, Inc. (PO Box 449, Yuba City, CA 95991) has just introduced all-stainless steel 12-ga. shotshells (2 ¾” and 2 ½”) formed at the base to take standard number 11 percussion caps. No loading or priming tools are needed – simply fill with black powder, 50 to 70 grains of FFG being suggested, add a card wad or plastic shot cap, pour in 1¼ oz. of shot, place a card was over the pellets and push the cap on the integral nipple.

You can, of course, vary the shot load, too, but in any setup use a fair amount of pressure on the over-powder wad and on the over- shot wad for best combustion and performance. A wooden dowel or “short starter” works well, and snug-fitting cork or felt wads can be substituted if space permits.

CAI sells these S. S. shotshells for $7.95 each or two for $14.95 postpaid, and a detailed instruction pamphlet on their use is included. They’re guaranteed for life.

Of course, a lifetime guarantee may not be for your lifetime, but the company’s — whichever comes first. The guarantee only works if the company hangs around. California Secretary of State records show that Conversion Arms, Inc. was registered in 1977 and at some time after that — the records don’t say — was delisted for failing to pay taxes. (That usually happens when the company goes paws up).

English Hooper (probably W.C.Scott) damascus barrels. Another GunBroker sale (higher end).

English H. Hooper (probably made for Hooper by W.C.Scott) damascus barrels. Another GunBroker sale (higher end).

Amber’s write-up seems to have been that old journalistic dodge, a paraphrased press release, but it makes us wonder why this idea flopped. We’ve often looked at some beautifully crafted old Damascus gun and passed it up, just because there’s no shooting it. (Maybe there is, now, with cowboy-action driven blackpowder loads. We dunno). But these simple shells would have made it possible to pattern Ol’ Betsy and take her hunting again, and that’s something. Why did they die? Were they too odd a product? Did they appeal to too narrow a public? Was the price too high? In 1979, a cheap imported double-barrel shotgun still listed at $179. The rock bottom of the market, the H&R Topper Youth Shotgun and its Iver Johnson knock-off, were $65 and $55 respectively. It may just be that for the few of us crazies who want to shoot an old shotgun more than the latest trap gun made in a workshop in Italy where Michelangelo once apprenticed in the stock-carving shop, brass black powder cartridges available now are good enough.

This all happened almost 20 years before the Internet went public and interactive, and so, before the event horizon of the net, we were unable to find a single write-up or photo of these things online.

As we mentioned, there is an alternative: although the shells don’t reinforce the chamber the way stainless steel ones did, Rocky Mountain Cartridge sells lathe-turned brass shotshells and a loading kit (.pdf). The prices vary by gauge and length; the chambering of most old American shotguns, 12 gauge 2½”, costs $75.00 for a minimum-order box of ten (.pdf) — the same unit price of one of the Conversion Arms shells, but in deflated 2016 dollars. The loading kit is another $60 or so.

This entry was posted in GunTech, The Past is Another Country on by Hognose.

About Hognose

Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).

26 thoughts on “Whatever Happened To… Stainless Steel Shotshells?

Larry Kaiser

I experimented with GI all brass shotgun shells. They were riot gun loads, OO buck. They took large pistol primers and oversize wads 11gauge or so. They worked ok but I had trouble keeping the overshot wads in place. Elmers glue worked but left a residue in the cases. Since I could not duplicate the factory radius on the mouth of the case they were a little difficult to load in a hurry. If you use them with black powder you will have to clean the black powder residue out of the cases or they will be ruined.


Alternatively, just use a steel sub caliber insert barrel.


Many types available, and you can just use (cheap, quick) modern smokeless ammo instead of black powder home made reloads.

Dyspeptic Gunsmith

Contact these guys and ask about your Damascus barrels and pressures:


Dyspeptic Gunsmith

Oh, sorry for a second short comment, but I can’t edit the prior comment:

Another way to shoot a Damascus barrel is to sleeve the barrel, and shoot sub-gauge cartridges. For that, go to these guys:


This is what I recommend to customers who want to shoot an old gun with modern loads and not have to buy special, low-pressure loads. You just slip in a Briley tube set into your 12ga, and you’ll be shooting modern 20 ga. shells to your heart’s contentment.


My understanding of the problem, is that the old guns with Damascus barrels (more properly called pattern-welded) have inherant flaws that will eventually fail no matter what shells are used.

The two slightly different metals, combined with highly corrosive BP and primer combustion residue, and added moisture, form a whole bunch of corrosion sites right where the metal has a built-in seam.

Sooner or later, it will fail.

Modern shells are vastly higher pressure, and the pressure curve is all up front. The guns were never designed for that.

BP loads are lower pressure, and a slower curve. Much easier on the guns, except corrosion plays a role unless cleaned immediately.

-if- the gun is in good shape, per professional inspection light BP loads -probably- are safe. But, sooner or later, it will crack somwhere.

Those metal shells do nothing to protect the barrels, by the way, just the chambers.

Personally, i would not plan on shooting Damascus. If i did, it would be a light BP load i rolled myself.

Cleanup of the gun is hot soapy water, then ballistol and water, then ballistol. Easy peasy and quick.

By the way, Cowboy Action Shooting is a real hoot! Especially for we “Darksiders” sometimes also known as “soot lords”.

Dyspeptic Gunsmith

There’s two large reasons why Damascus barrels got the rep they now have:

1. It was to arms companies’ benefit to scare the pants off gun owners 100 years ago with tales of ruptured Damascus barrels in order to get people to buy a whole new line of shotguns with barrels made from “fluid steel,” “ordnance steel,” etc.

2. Most people don’t know that many low-end shotguns of the 19th century were made as “side door specials” out of shops in Belgium. Real, quality barrels would be proofed, but the barrels they’d export to the US for “trade guns,” would often not be proofed, and often they’d be knocked out after hours or on weekends to augment the workers’ take-home pay. There were lots of really crappy, single barrel shotguns, sometimes called “farmers’ guns” that were made to a very low price. If you put even a AA load of smokeless into these guns, they’d fail – in more ways than just the barrels.

W.W. Greener had proof tests run on his Damascus barrels by the Birmingham proof house, as well as proofing alloy steel barrels. Greener had the proof house keep cranking up the pressure – and they found that the alloy steel barrels failed first. Now, I’m not saying that all Damascus barrels are of the quality of the Greener barrels, I’m just pointing out that you have to choose your Damascus. As in so many things, when you pay for quality, you might actually get quality. There were several British and US sources of Damascus barrels that were quality products in their day, and if they were cared for, they’re still quality guns now.

Damascus barrels are one of the most contentious subjects in double gun smithing today. All I’ll say is that a well made Damascus-barreled gun of 100 years ago will attract my attention as few other guns will.


To avoid the debate about the damascus/pattern-welded terminology, I’ll call them forge-welded steels.

Yes, in theory, forge-welded steels will always have a much higher potential for flaws than monolithic steels. Every weld introduces a potential failure point, every folding adds another chance to pull apart a weld. Corrosion will also be more pin-pointed, as one of the steels will be more rust-resistant than the other (hence the pattern).

But it always depends on what you compare it with and who makes it:

– Forge-welding for patterns is a bit complicated, so usually the work was usually done by someone of a higher skill level.

– When compared to a modern industrially made mono-steel, there is not doubt that the latter is better. But around 1900, several methods of steel making where popular. The Bessemer process did make comparatively good homogenous steels, but some “puddling” techniques were still used. Re-welding steels was actually used to purify it (the Osemund/Osborn process lasted until late 19th century), so forge-welded steels could even end up more pure.

– When talking about modern mono-steels, one should use modern damascus steels like Damasteel ™ from Sweden for that comparison. There are no welding flaws in their steels (yeah, I’m a bit of a fan, the owner is a really cool guy). Since these are high in chromium content, rust is also not an issue. You’ll be paying a lot more for looks, but there will be no performance issue.

– There always the question about what’s optimal vs. what’s good enough. If you started out as a purist knife maker like I did, you’d be busy shaking your head what cheap, crappy material passes as “good barrel steel”, as barrel steels are chosen for cost-effectiveness (turning on a lathe needs to be easy). If you give up on that, because you’re building a premium product, there is a lot of modern damascus steels that will satisfy all other requirements.

— For illustrative purposes: I think it was Cabot guns offered a friend of mine to make a gun out of his own pattern-welded steel (high carbon content, no soft decorative layers). His hand-made steel tends to have some flaws, but it was still judged good enough. The condition was that he paid for the tool wear, which would have been tremendous, so he gave up on that idea.




RMC makes good brass. I use it in 4, 8, 10, and 12 bore rifles.

There are a ton of myths regarding damascus barrels. In good condition they’re just fine to shoot, even with modern loads. Refer to Sherman Bells excellent testing reported in The Double Gun Journal where he trys to test to destruction a pile of $50 shotguns in damascus barrels using modern 12 gauge proof loads. In most he could get no dimensional changes.

Published pressure testing shows many BP loads actually have a higher peak pressure than modern smokeless rounds and as noted above, that peak occurs sooner. I use smokeless (Blue Dot to be specific) in all of my bore rifles except a damascus 10 double rifle that only shoots well with black. Same ballistics, MUCH less recoil, lower pressure, and easier clean up.

Hognose Post author

4 and 8 bore rifles…. (assumes position of supplicant) can I touch the hem of your garment?


Hog, you can do even better and visit Anchorage for one of our double rifle shoots and shoot several of them!

We get together at a local range about twice a summer to shoot, check out each other’s guns, and cook out. Very informal, free, and open to all. Last shoot was May 7th and the next is the second Sunday in August. We usually try to time the spring one with the Avn expo or some other event in down so out of staters can hit both in one trip. Search google images for “Alaska double rifle shoot” for some pictures of previous events. Usually about 50-60 double rifles, mostly British, but I always bring a few machineguns to mix it up. Everyone’s invited.

If you shoot me an email I’ll send a link to a short vid of my 4-bore on a water buffalo hunt. I work quite well with 1500 grain balls at 1525fps.

Back on topic, the RMC brass are so expensive because they are turned from bar stock rather than drawn. That means they have the same thickness as a paper or plastic case. As noted above, the drawn cases that us pistol primers have a much larger interior diameter due to their thinness, necessitating using 11-gauge cards in 12, etc. Not a big deal with shot but could be when loading bullets. I’ve got rifles that were designed for each.

The other advantage is that RMC will CNC brass to your dimensions if you send them a chamber cast. With so many variations on chamber and bore size (I’ve seen “8-bore” rifles in .809″, .820, .835, .840, .845, .875, and .888″ bore diameter!!!) this is a godsend. I’ve got well over 50 reloads on some of my cases and they are still in perfect condition.

Hognose Post author

I’ve heard that no two maker’s four-bores had the same size cartridge, and lathe-turning was how they made them back in Britain.

Dyspeptic Gunsmith

4 & 8 bore rifles are a hoot. One of my gunsmithing instructors made a couple of 4-bore double rifles that imitated the H&H rifles of 120 years ago. He had to make literally everything on the gun, because there are no sources for a receiver, barrels, etc. Every time he makes one, he says it takes about four years, start to finish. He’s obviously working on other projects along the way, but it says it’s a heck of a lot of work. Starting price is about $25K.

Overall weight is about 25lbs. Using BP, he says it is more of a hard shove than a recoil punch. His clients used these guns for African hunts. The feedback he received was that Cape Buffalo actually stop in their tracks when hit by a 4-bore.


My 4-bore is a single shot from ~1887 and is engraved “For Kynoch’s drawn case.” I’ve never seen a kynoch 4-bore case, but as I think there were probably less than 150 rifles built by all makers combined I tend to agree that no two companies used the same dimensions.

My 4 is a “thin brass” gun and the mouth is an extremely thin .004″ at the mouth. It thickens to .027″ just below the bullet. It’s bore is 1.005″, but I also have a damascus shotgun barrel for it that uses the same cases but necks down to .938″ after a 9″ forcing cone and then chokes to .890″ at the muzzle. I can only imaging the explosion if you were to fire a rifle round in it.


I wonder how much additional strength the stainless steel hulls added to the chamber. I know there was a test done to see how thin a shotgun barrel could be made. Can’t remember how thin a wall thickness that was reached before bursting; I know it was surprisingly thin though.

Dyspeptic Gunsmith

The test was done by Parker Bros., I believe the test was done in 1912, on “fluid steel” barrels (ie, semi-modern alloy steel) and the test found that 3″ forward of the chamber (where people reckoned the pressure maximized) they got the barrel wall down to 0.012″ thick before they started seeing deformation from a single shot. Somewhere in my reams and reams of paper and books I’ve collected, I have a copy of the article from a machinists’ magazine on the issue. The same magazine also ran articles on how Parker Bros. matted their ribs on a horizontal mill, which was fascinating as well.

Most folks also don’t understand the actual pressures involved in shotguns – about 9K for a light trap load, about 11K PSI for a field load. A proofing load will be only in the 16K+ range. Modern rifle cartridges (eg, many designed since the early 1960’s) will be over 60K PSI. The 5.56 NATO round is running about 62K PSI MAP (Max Average Pressure). A black powder load will be in the range of 6K to 9K PSI, but the pressure curve will be sharper on the increase, and decrease very rapidly as the shot/wad move down the barrel.

Most people don’t realize the benefits that having a proof house brings to firearms construction. In the UK, you have to provisionally proof a barrels before they are made into a gun, then you make the gun, then you send in the completed gun for final proofing. The result is that British “best guns” have substantially thinner walls (say, 0.020 to 0.025″) than American high-end shotguns (0.035 to 0.040+”), because in the US, we’re forced by our liability jackpot system to use very high levels of safety margin in gun construction. There is no government-run proof house in the US to shield gun makers from liability, so the only way to avoid liability is to over-build guns to a point where, if they blow up, most any engineer with even a modicum of honesty will say “Uh, yea, there’s no reason that gun should have failed without varsity-level stupidity on the part of Bubba The Faceless…”

The result is that the Brits have light field guns that leap to your shoulder, and we in the US have guns like the Winchester Model 21, which feels as if you’re mounting a flak cannon to your shoulder. The Win21, however, was tested by Winchester to have shot over 2K proof loads in a daily diet of shells for weeks, then measured to find no dimensional changes in the shotgun whatsoever. The Win21 is build like a flak cannon, because they wanted to build the shotgun that Bubba could not blow up.


“Most people don’t realize the benefits that having a proof house brings to firearms construction”

I never realized that the awkward combination of the US’ lack of such a thing plus the liability laws.

Thanks, that clears a lot of things up.


Posts and comments like this are the reason I come here and I learn something every time! Fantastic stuff!!

James B.

The information in just this comment section is literally priceless to a lover of ye olde damascus double guns. Thank you to everyone here!


Roger that.

Light Dragoon

Neat! I have a pair of those “shells”, and wondered who had made them. I just figured it was a cool way to reload, using percussion caps and black powder for a quick in-the-field reload for a black powder cartridge shotgun. Now I know! (Not that I have any intention of using them in most of my Damascus-barreled shotguns, but that one little Lefever, well, I might just use it in that one…)

Anyway, thanks for posting that. I always learn something from your posts, and this was definitely no exception.

Hognose Post author

Cool. Thanks for reading, and for commenting.


One of my old shooting books had my absolute favorite picture. A guy is loading a BP shotgun from the muzzle and he is using a scoop to put the powder in! Gotta love those old time guns.