Converting centerfire to rimfire

J

johnwilliamson062

Moderator
I'm thinking offset inserts for the chambers. Those could be loctited in and not permanent. Could be long enough to function at low velocity with-out augmentation of the barrel.
I COULD drill the barrel and add an insert. The insert would have to be off center to match the chamber insert offset. Drilling that offset with a pilot hole already present would be the hardest part. Maybe with a bushing.

Probably start in either a Colt police positive with an obsolete(as defined by me) chambering, or maybe a Nagant revolver.

Anyone want to comment as to how close the liner and barrel need to line up? Actual dimensions, not "real close." .002 ok? I could install the barrel liner first along with chamber insert blanks, then indicate the bore and drill down it with a thin pilot drill(I can probably get a discarded dull one from work and sharpen it), then indicate the hole created on the cylinder and finish from the other side with the cylinder removed.
 
Chambers in the cylinder inserts could be made to diverge to get the rim under the firing pin.
Put a blank insert in a chamber, mark the centerline of the bore with a punch down from the muzzle; drop the hammer to make a mark where the cartridge rim should be. Calculate to locate the center of the casehead, drill to connect the two centers, run in a chamber reamer.

Or you could just line the barrel, bush the chambers straight, and make a new firing pin bushing and firing pin. You know, like Colt did it.
 
anything is possible... I have an antique 30 rimfire spur trigger revolver in my collection... I won't keep anything, if I "couldn't shoot it" well 30 rimfire ammo is very obsolete... I had my machinist buddy make me some eccentric rifled chamber inserts from a chunk of 22 LR barrel... then chamber those in 22 long, a little sleeve retainer hold them in place, but they could still be pushed out if needed... so I can now shoot 22 Colibri's in the gun... only about a 1/2" of rifling, in the chamber inserts, & did nothing to the 30 caliber barrel... the gun could hit a man sized target at 5 yards, which was all the gun was good for in factory chambering :)
 
A good look at the cartridge conversions cylinders for black powder revolvers might give one some ideas. Most of the original conversions used reshaped hammers to fire a center fire cartridge but I don't see way it won't work with 22 rimfire.
 
It has been done, many times. The idea works OK. The problem is that after the shooter tries it a few times, he says "cool" and goes back to having two separate revolvers, because loading and unloading the inserts is just too much of a pain. (If the conversion is permanent, then there is no advantage over just buying a .22 to begin with.)

FWIW, the S&W Model 53 has two separate in-frame firing pins, with a movable hammer nose, so the chamber in the adapter is not offset.

Jim
 
You'd be surprised to see what's in peoples safes:D.

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I'm looking at permanent or very close
The reason? I can purchase some old centerfire revolvers in obsolete cartridges for hundreds of dollars less than their rimfire counterparts in like condition. Nagant revolvers for instance. I can get a centerfire fo r under $200 and pretty much just spend time on it after that. If i buy a barrel liner that will obviously have a cost also.
The inserts above do look like a pain. Why I want o go with offset chamber inserts.
I may have to make another ejector star or convert to moonclips also. 22lr moonclips...
This may be my project for next winter.
 
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To solve the offset barrel liner problem, that would be needing to drill a 4"-6" deep hole off center of an already drilled hole with tooling available to me. Have no idea what a 6" long endmill of that small diameter would cost, and no idea how to drill it without the bit following the pre-existing hole and snapping.

I drill out the bore oversize to the max possible. I then turn a solid outer liner that fits within the new bore ID. I then go and remove metal from the channel to fit the barrel sleeve. Maybe. Probably using drill and reamer. I think I will have sufficient diameter since the barrel is originally intended for .32, .38, or .45 depending on host pistol. Just hve to look more into the .22 barrel liners.
 
For a permanent conversion, why use offset inserts at all? If you have any decent shop, it is not very difficult to convert most hammers/firing pins to rimfire, using welding or other means to change the frame as necessary. Then you just solder or epoxy the inserts into the chambers and the liner into the barrel and you have a rimfire revolver made from that old 10mm Italian or whatever.

I once fired an SAA Colt that had been converted to .22 just that way; it worked fine, though heavy as heck. (Yes, there was a reason Bill Ruger scaled down the Single Six!)

The advantage is the same as the disadvantage: you have a .22 rimfire revolver with a poor grip, bad trigger pull, and horrible handling characteristics.

Jim
 
One of the reasons I like the outer barrel bushing idea is I can use a material like aluminum or possibly titanium to reduce forward weight. Titanium for chamber inserts. Weight may be less than original.
Now the trigger, I am sure a S&W, Enfield, or similar can be made as good or better than most 22lrs.

I can think out seveal options for the offset solution that are within my capabilities. I will have to get my hands on a pistol and think about it before I can come up with how to do the firing pin/frame modifications.
 
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