Slocum Rimfire Revolver at RIA

The Slocum revolver, designed by Frank Slocum and manufactured by the Brooklyn Arms Company, was one of the more successful workarounds for Rollin White’s patent on the bored-through cylinder. The most significant advantage of Slocum’s design was its use of standard .32 rimfire cartridges, unlike most other workarounds which used proprietary ammunition. Slocum did this by using a very clever chamber sleeve idea, in which the chambers are actually separate removable pieces that fit in the cylinder.


  1. This isn’t a bored-through cylinder! It’s an idiot-proof rotating cluster of chambers! While it is probably more expensive than a Smith and Wesson, it has better “maintainability” in that a damaged chamber does not require you to buy an entirely new cylinder or gun. Just buy a replacement chamber piece instead and save yourself a ton of money. As for the chamber pieces themselves, they seem similar to the links in a disintegrating metallic MG belt in concept.

    Am I wrong on any of the claims in this post? SAY SOMETHING!!!!!

    • As I recall, that Rollin White patent was good for 17 years, White didn’t do much else than sue infringers, and we had a Civil War during that time. This is the best no hole through evasion I’ve seen.

    • I actually really like it, with a bit of tweaking it might even work as a legitimate system on it’s own and not just a ‘work around’. Also because I’m just weirdly fascinated with the concept, I’m wondering if it would be possible to combine with a nagant style action so the chamber was pushed forward to create a seal with the barrel instead of the entire cylinder, in order to create a silencable revolver with a better trigger pull than the nagant.

      • If the barrels… Forcing cone is it “The back of the barrel that pops out into the cylinder gap” was of a larger internal diameter than the chamber, upon firing you could imagine the chamber moving into said bit by itself, you’d need to extract it again to rotate the chamber, but perhaps some sort of rack and pinnion lark, could do that when you re-cocked the hammer. The axis pin could be a rack, on it’s upper side, and the chambers thumb grooves the pinnions if the grooves were inverted, then link the axis pin to the hammer by a pin which allowed the axis pin to pivot type thing with the hammer going back and forth.

        • Actually the rack could move it forward as the hammer fell, the chambers “pinnion” groves would have to rotate into those on the rack per turn of the cylinder like, be a gap, perhaps the rack might need to disengage and re-engage from pinnion, as you only want it to go forward and back a bit. Hmmm, conical axis pin, with a semi circular pinnion block piece that would sit around the axis pin, being pushed up and down via it’s cone shape, they’ll be ways.

      • The Nagant can have a fairly nice trigger in single action mode, since it’s the cocking action that seals the cylinder. There are even people who do trigger jobs on Nagants.

    • The “cylinder” (actually a better term would be “rotor”) works a lot like the feed rotor of a couple of Russian MGs, The DShK M1938 12.7mm and (IIRC) the ShKAS aircraft gun in 7.62mm. In their case, the “rotor” was used to move the metal-link feed belt.

      In the 1970s, a tear-gas pistol, the GG-31, used a setup similar to this. It was a four-“barrel” DA-only thing, rather like the old Mossberg Brownie, but instead of conventional barrels it had four cylindrical openings, each of which took a 3/8″ OD aluminum tube full of powdered CN tear “gas”. The propellant was a special .31 rimfire blank made by CCI-Omark that fit in the back end of each aluminum tube. You slid four tubes into place, and secured them with a knurled, threaded screw at the muzzle end that overlapped all four just enough to keep them from sliding out.

      The four CN “shots” reached out about 10-12 feet, and included a dye that fluoresced under UV light, which was handy for identifying the perp afterward.

      Some PDs issued these as ‘backup’ weapons, notably to plainclothes officers. They were also offered for sale to civilians, apparently, but I don’t recall ever seeing one anywhere.

      (Source; Law Enforcement Handgun Digest, by Dean Grennell and Mason Williams. DBI, 1972. PP.140-143.)

      As for the “advantages” of the Slocum, they don’t really stand up 8nder close examination.

      It may indeed be easier to load in the dark than a percussion revolver, but why would you wait until a housebreaker is in the house to load it? Besides the chances of fumbling the drill, there’s a good chance he’d hear you.

      Rotating the round in the chamber for a second strike at a dud? The IA drill for a dud in a revolver is called, “recock and pull trigger again”. That’s rather the point of any revolver, especially a DA one.

      As for ejection, it looks to me like the fixed ejector rod can only push the empty round about 1/8″ out of the chamber, unless it bears on the case mouth rather than the head. So it’s really not all that much faster than the “remove the cylinder and use the fixed rod under the barrel” drill of the S&W. In fact, it’s probably slower.

      All in all, the Slocum is an interesting gadget for the way it gets around the Rollin White Factor, but even in its own time it would have been more of a novelty item than anything else.

      A serious defensive pistol? Not all that much.



        • It wasn’t even brand new, there were flintlock revolvers… Of a sort, presumably with bored through holes in there cylinder.

          • Maybe not, oh well fair enough someone had to patent it I suppose, I mean with hindsight it seems a pretty obvious development of a percussion revolver after the metallic case came about.

      • “All in all, the Slocum is an interesting gadget for the way it gets around the Rollin White Factor, but even in its own time it would have been more of a novelty item than anything else.

        A serious defensive pistol? Not all that much.”
        For me it looks as a feasible design for multi-caliber (using different cartridges BUT with equal bullet diameter) which could be easily converted by changing the sleeve. In fact you could even mixed different cartridges in one cylinder.

  2. Maybe I missed it Ian but what year did that pistol become available and how long were they produced?
    Did they make in any larger calibers, looking at a military contract?
    What did they sell for at that time?
    Excuse the next comment but– it appears to take a rim-less straight cartridge.
    As I look at it, the pistol does not lave the added diameter in the rear of the cylinder that would accommodate a rimed cartridge? Just my ignorant observation– I’m likely wrong as you are a better judge than I in these matters.
    Thank you. I enjoyed your presentation.
    Do you know anyone that might have a Lewis for sale?

    • Hmmm, do you mean the cartridge rim would sit on the rear of the chambers rim Patrick… There’s an indent in the cylinders back plate for each chamber, but it the rim of the cartridge sat on the rim of the chamber the chambers would protrude from the cylinder at the front somewhat I think “from what I can make out” There’s a cylinder gap, but the barrel pops into it pretty much. Maybe the chambers don’t have a rim “lip” in them as such, but are sort of coned, so the case headspaces off it that way type thing, the hammer seems to hit the case straight on at it’s top presumably that would still fire it.

    • No, there IS a groove for the rim of the cartridge. Look CLOSELY. Everything I’ve seen for the Slocum gives a date of 1863. That means the ONLY choices for cartridges would be .22 or .32 rimfire.

  3. That’s pretty swell, it would be a good cylinder design for these 3D printers, or Polymer clay these days probably.

    • They could have got away with a brass cylinder probably, a varient of that design might have been alright in percussion actually… Lose the ejector rod, and have the chambers bored narrower towards the muzzle end, drop in a ball from the rear “the narrower part, holds it” powder behind, close it- cylinder loaded, increase the indent in the cylinders back plate thing for each chamber this would have nipples on the other side obviously, cap job done. Possibly less of a gas seal, and as we saw in the slow mo, cap firing video, caps make some sparks anyway, but given the partial encapsulation of each chamber I wouldn’t think it would be anymore at risk if chain fire, might get fouled though with black powder… Maybe the oil holes, were more to do with oiling the chambers rather than the axis pin, early rimfires used Bp in a case I know, but maybe some fouling could get between the chambers and cylinder at the firing end via the blast happening in the cylinder gap.

      • Move the ejector rod forward, so it just act’s as chamber stop at a point were the chamber is still in the cylinder obviously, it could swivel around the barrel to allow the chambers to be removed.

  4. I’d say that the oil hole had a very valid reason to be there. Even tools like a screwdriver weren’t owned by a lot of people back then.

    Even my two grandpa’s who lived from the late 1890s to 1970s didn’t really have tools and neither would have had a screwdriver that could have been used to remove that screw.

    While the both farmed well into the modern mechanized era, they didn’t ever really get tools.

    My paternal grandpa owned a hatchet, a single sided ax, a double sided ax, a board ax, a general purpose screwdriver, and one monkey wrench. If he had to drive a nail, he used the hatchet for small nails and his single sided ax for spikes. He didn’t remove nails, he removed wood with an ax instead. If a board had to be cut to length, he used an ax or hatchet.

    He was very good with an ax, as was most of the guys of his era. I remember seeing other using a hatchet for things we would never use one for. My uncle told me once it was because of the amount of firewood that generation had to cut and split when they had been young. With their brothers they have a competition to see who was the most accurate at cutting the wood. You all know the old saying about Germans, “They make work into play and play into work” and I think that saying is a least somewhat universal.

    Sometimes we don’t automatically see or understand the reasons something was done the way it was many years ago.

    Another example is US made maypole braiders which I’ve happened to work on. They last redesign was done about 1880. Due to the expense of machining back then they maximized the number of parts that are used as cast. So the holes were cast large and even when they started to machine these parts after WW2 they had to machine them large.

    What goes into these holes has of adjusted with shims and a screw to align properly. Of course that alignment is based on some that one aligned the same way. Guys who work on them but don’t under the history of manufacturing them a braider that could be used as a paint shaker that also is parts breaker.

    • “Even tools like a screwdriver weren’t owned by a lot of people back then.”
      This reminds me of Marlin Model 39 lever-action take-down rifle, which has distinctive screw designed to be screwed/unscrewed with coin.

    • If I remember correctly, the Ford Model T’s came with a tool kit that included all tools needed to do any maintenance needed on the vehicles. That would not have been needed if people tended to have ready access to hand tools back then.

      • Honda motorcycles into the 1970s at least came with tool kit that include a feeler gage to set the valve.

        When I was staying a 3rd world country a few years ago, the guys that I got to know all wanted me to send them a US made vise grips. The Chinese made ones broke and a vise grips was the main tool they needed to work on their motorcycles. When I got back to the US I cleaned out the nearest hardware store. Cost more to send them than the purchase price.

        Interestingly I found that many owned unregistered handguns. I didn’t get to shot one as they, as most, only had enough ammo to fill the magazine. Most had never even shot them. I did them some pointers on reloading in such situations.

  5. @Daweo
    I said it would be easier to machine chamber sleeves rather than the entire cylinder. And the sleeves would be considered “replaceable” parts too.

  6. Heavy DA trigger of Nagant is a must. When the cylinder is on forward mode and case mouth swaged into the cone type recess into the barrel, the cylinder return spring may not provide power to retract the cylinder to its back position and a small lug at top of pulled back trigger forces it agaist to the shoulder carrying the cylinder stop notches over it as using the very big leverage through the trigger axis, carries the sticked forward cylinder to its rearmost location. Nagant triggers can and should not be softened.

  7. The design could allow for multi-caliber revolvers. There have been a number of designs over the last few decades of pistols that had the ability to change calibers (H&K, Sig, IMI, etc.) but I’m not sure any of them did very well. In theory it would cater to those who would have a hard time owning multiple pistols due to legal issues. But so far it seems like a solution in search of a problem. Is there really a big call to be able to go from 9mm to 45ACP, or 9mm to 41AE, etc?

    But it might make very good sense to make a large bore revolver that would normally be used without sleeves (i.e., a normal cylinder), then have the capability to use sleeves to go with smaller caliber rounds. For example, start with a 44 caliber revolver, then be able to power it down to 22 LR. Go with 22 caliber barrel inserts that could be secured by a treaded ring at the barrel muzzle. Something that could be swapped in and out with no tools. Especially if the rear sight were to have some markings or such so one could quickly dial back and forth between two settings. Maybe the recoil shield and transfer bar assembly could be indexed up and down to go from center fire to rim fire positions.

    Having a revolver that could fire big game hunting cartridges and then be capable of being dialed down to 22 long rifle would cater to those who were going to pack one revolver into the back woods. It would give them the ability to have a serious side arm, but then switch to 22 long rifle for small game and do so for only a few ounces of parts to pack along.

    • “start with a 44 caliber revolver, then be able to power it down to 22 LR”
      There is conversion (barrel & cylinder) for British .455 Webley which fire .22 rim-fire ammo, see photo there:

      “In theory it would cater to those who would have a hard time owning multiple pistols due to legal issues.”
      If so Medusa Model 47 seems to be best solution.

      • Thanks for the link. Wish I knew how the device accommodated the center fire firing pin to rim fire. For revolvers currently manufactured, the design might be most adaptable to single action revolvers, as those cylinders can be traded out without the use of tools.

Leave a Reply

Your email address will not be published.