Converting top break revolver to 25ACP

This looks like it should work in a top break designed for smokeless powder. I would reline the barrel, sleeve the chambers, and install new sights. Ejector looks like the most challenging part, sleeves to solder on.

Another option would be a CF version of the old Stevens RF. Use 22 Hornet brass.

Third and fourth options would to convert a single action 22WMR, relocating the firing pin would be the challenge there.

Some pitfalls along the way that I likely glossed over. Comments or suggestions welcome.

You don't say what model you are considering converting and that is a major concern. If it is any of the old .32 cal cartridges, SAAMI rates them in the 12000-13000 CUP pressure range while .25 Auto is about 18000 CUP.

This seems to be a not very good idea. Why don't you want to use the original cartridge?

Why? As a challenge to myself and an interest in 25 caliber revolvers. Starting with a 38 S&W, not Special, as it seems more common. Peak pressure is higher, but spread over a smaller area, plus there is more metal to contain the pressure.

Realistically, a 22RF can do what I usually use a pistol for. This would be an interesting project.

You could make your own tiny half moon clips.

Might be enough rim for a tight'ish chanber?

BobYates said:

This looks like it should work in a top break designed for smokeless powder. I would reline the barrel, sleeve the chambers, and install new sights. Ejector looks like the most challenging part, sleeves to solder on.

Another option would be a CF version of the old Stevens RF. Use 22 Hornet brass.

Third and fourth options would to convert a single action 22WMR, relocating the firing pin would be the challenge there.

Some pitfalls along the way that I likely glossed over. Comments or suggestions welcome.


Why? As a challenge to myself and an interest in 25 caliber revolvers. Starting with a 38 S&W, not Special, as it seems more common. Peak pressure is higher, but spread over a smaller area, plus there is more metal to contain the pressure.

Realistically, a 22RF can do what I usually use a pistol for. This would be an interesting project.

Click to expand...

Had a folk I know do pin relocation - said it's been the most annoying part, so good look with that. Can see sleeves being an issue too as you mentioned. Looking to be a pretty interesting project, would love some updates in case I decide to do something similar.

I have been thinking on a similar idea for awhile now. The 9mm Makarov round in full moon clips would be almost a perfect fit in the old top break .38 revolvers. The Russians have developed a version of this cartridge specifically for defeating body armor, a very likely thing to encounter in the course of personal defense in our crazy new world. The problem with any of the old top breaks is that the pressure threshold is just not there. If you would listen to the fellows on the firearms forums who have vast experience with these old revolvers, you find that even with equivalent pressures of smokeless powders in any of the black powder frames (the vast majority BTW) the frames stretch, peen and get out of order quickly because the pressure spikes differently. I think the solution is to replicate the revolver, frame and all out of 4140 series tool steel before any serious work can begin.

Please elaborate on the firing pin conversion CF to RF. I have a half dozen H and R Auto Eject frames, all centerfire with the "removable" bushing. Problem is I can't find anybody who can tell me how to remove the thing without damage, and whether it presses in from the front or the back. Once out, making the new RF bushing should be a breeze, but the hammer maybe not so much.