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This .22 rimfire 1911 that I did for a friend a few years back has been…. well, a pain. It just never worked. The floating chamber would lead-up in 5-8 rounds rendering the gun inoperable. We talked about it and Fil said he’d work with it on ammo selection, etc. I could not bring myself to believe that none of them ever worked and yet—there was nothing really evidently wrong with this one, although it was the only one I’d ever worked with. I thought the jump from the floating chamber to the barrel should have a revolver-like forcing cone, but it didn’t…. still I thought, it’s a Colt, they’ve made these by the train load and as far as I know they don’t have a rep for not working. We’re missing something.

Recently, a few years later, I visited Fil and the gun and…. it was still not working. I took it back and looked it over. I gave it that forcing cone—I went 4 degrees to .228 diameter, then 1 degree leade.
Halelujah, it works! First sixty rounds and no leading, cycle is brisker and lockback with six different loads is positive (it was intended and touted to recoil like a .45).


.22 bbl with floating chamber. In battery, it is forward. Upon firing, the rear piece becomes, essentially, a gas piston and cycles the slide positively even though it is not lighter than a standard .45 slide.


Floating chamber detail.

I had one of those once. Ran pretty well. Could run at least a box or two of shells through it without any stoppages. Traded it off. Seemed like a good deal at the time.

From about a year later, and thirty plus years to the present . . . not so much so.

"Thanks" for reminding me ;~(

Kudos! Thinking outside the box to find a solution to a problem is a sign of a real gunsmith.

Well... I wonder if what really happened was it just didn't get done at the factory? Concentricity between the floating chamber and barrel bore was good so it wasn't that....

Last week I had the opportunity to examine two other Conversion Units and they both had generous leades / forcing cones.

The above one, once I got it working-- which was easy in the end-- I found it was not as accurate as I had expected. The barrel was rough on the inside. Not from use, misuse, or rust, just-- rough. Rough. Made that way.

I scored a length of barrel from a Suhl target rifle-- these are on par with the best Olympic rifles out there..... and I lined the Colt's barrel with it.

It's better but still not a one-holer, sofar anyway. A whole lot of work probably mostly wasted; I think now that these Conversion Units are simply not the pinnacle of .22 accuracy. Probably shoulda done my homework. When I get around to it I think I will find these never had a place in Bullseye because they were easily out-shot by High Standard Victors and the like.

Sleeved. Shrunk, pressed, pinned!



....and, the "why" of sleeving it. The original barrel inside:


The result of sleeving it with the Suhl barrel-- dang thing was more perfect than any rimfire barrel I've seen:


...and quite a bit more accurate than I thought. Worked with it quite a bit more today and with a wide variety of high-pie target ammo.

It prefers Aguila and Winchester, hallelujah. Still probably not a Camp Perry contender but much better than the original Colt barrel. And is cycles very briskly like it's supposed to, I almost thing it would cycle with shorts.

That is a beautifully rifled barrel!

I already have put more time into this that I should have but I wish I'd had time to chrono some loads in the old and new. Something as smooth as this Suhl barrel surely give a few more FPS...?

Epoxy, soft solder, or what to secure the sleeve??

Old barrel reamed 3/8..... passes a .3752 pin but not a .376. I turned the sleeve to about .3755. It had a "head" on it so pressing it in from the front it stopped at the right depth. I put the sleeve in the freezer and warmed the barrel which made for a just-right fit, tapping it in with a lead ball. Then it has the three 3/32 cross-pins that are about .045 from the bore.