22 conversion. 22 LR to 22 magnum

[Polizei45]

Greeting from cold Hamburg NY. ( Go Bills )

I have a S&W Model 18, 4 inch 22 LR. I found a brand new Model 48, 22 magnum cylinder and extractor. Will the cylinder work on my Model 18 since they are both K-frames. Thanks.

 

[Old_Cop]

Yes if the cylinders are the same length. A friend of mine did this with a K22.

 

[Dave.357]

There is a little more to it than that.
The new cylinder will have to be fit
To your revolver.
On my model 63 it was necessary to shim cylinder
to get right clearance.

 

[22hipower]

As Dave.357 says it will probably take some fitting (filing) by someone who knows what they are doing but it will work. I did the same thing about 20 years ago with a pre-18 and 48 22WRM cylinder. Works fine and I don't see any difference in accuracy between the cylinders but never did any detailed testing. Good luck.

Jeff
SWCA #1457

 

[Abbynormal]

I thought the bore size on .22 Mag was smaller than .22 LR?

 

[Smolt Smython]

From Sporting Arms and Ammunition Manufacturers' Institute:

SAAMI minimum specifications for barrel dimensions:

22 LR - SAAMI
Bore: 0.217 in (5.51 mm)
Groove: 0.222 in (5.64 mm)

22 WMR - SAAMI
Bore: 0.219 in (5.56 mm)
Groove: 0.224 in (5.69 mm)

Potentially you may encounter excessive pressure firing a .22 Magnum cartridge into a barrel that is .002 undersize in both bore and groove dimensions. This may vary from firearm to firearm and from different types/brands of ammo. I am only quoting the specs that manufacturers have agreed upon for your information, I'm not making any judgement on your particular situation.

Just as an additional comment I believe that the "convertible" Ruger .22 Single Sixes use the .22 Magnum barrel dimensions and accept a potential slight loss in accuracy with .22 LR ammo to avoid any pressure issues with .22 Mag ammo. Like wise the .357/9MM convertibles use the larger .357 spec barrels.

Additionally, my experience with S&W K and J Frame revolvers in .22 Mag is that apparently most (probably not all) .22 Mag ammo is optimized for rifle length barrels and a significant amount of the powder charge does not burn in a revolver. After several reloads this would lead to unburned powder getting underneath the extractor star and quickly making the cylinder function quite stiff, either requiring some force to operate or actually jamming it. This can be mitigated by always holding the muzzle straight up when extracting fired cases so that the powder residue falls away from the gun and not down onto the cylinder. I also used to carry a toothbrush with the handle cut off to about 2" and gave the under side of the extractor star and the breech face of the cylinder a quick swipe when unloading/loading.

I hope this answers some questions. Good luck with your project.

 

[SuperMan]

Have done four S&W .22 LR to .22 Magnum conversions...they all shoot great...
35-1
63
18-3
17-3

Also just did a 1954 Colt Trooper and a friend did a Colt Diamondback several years ago...

No reason not to...

Bob

 

[Hondo44]

I did that to a pre model 18. It happened to be a drop in. Not withstanding the facts and good advice above, I have no issues with mine and accuracy is very good. Even if some fitting is needed it’ll be minor. As long as you’re sure the cyl is not from a model 53 which are longer; either a 22 mag or 22lr reamed to 22 mag.

 

[cgt4570]

I've fitted a mag cylinder to a custom Ruger Bearcat and it shoots great.
I have near future plans to rechamber spare Smith cylinders for both a K and a J project. Most manufacturers have used the same barrels for both LR and Mag. Since rimfire ammo isn't hard jacketed, a couple thou. shouldn't make much pressure difference.

 

[Hair Trigger]

Additionally, my experience with S&W K and J Frame revolvers in .22 Mag is that apparently most (probably not all) .22 Mag ammo is optimized for rifle length barrels and a significant amount of the powder charge does not burn in a revolver. After several reloads this would lead to unburned powder getting underneath the extractor star and quickly making the cylinder function quite stiff, either requiring some force to operate or actually jamming it. .

I can attest to at least a small issue with unburned powder residue when shooting my 6" M48-4. I get an accumulation of tiny "cinders" of partially and unburned powder in the chamber throats and forcing cone, and when the cases get extracted, some of this follows the case mouths back to the extractor star. If it's an extended range trip, I'll take a barrel swab and run it through the barrel and chambers to clear the residue.

I would suppose my revolver also follows the MRF specs, and you take what you get if shooting .22LR through the barrel if you have the .22LR cylinder than was optional for the gun.

 

[stu1ritter]

I couldn't find a 48 cylinder but did come up with a new 648 cylinder. Mine had to be fit but it wasn't that hard to do and I had never done one before. The revolver is a lot of fun to shoot.

Stu

 

[glenwolde]

As you can see, lots of shooters have done this successfully. All I can add is that back in the day the factory would fit a LR cylinder to a MRF revolver but they would refuse to fit a MRF cylinder to a LR revolver because of the aforementioned difference in the barrel specifications. They were bound by SAMMI specs. I tried. They wouldn't do it.

That said, after a good bit of bench shooting I found the convertibles to have less than great accuracy when shooting the LR round. The LR cylinder did not shoot as well as the MRF, nor as well as an identical dedicated LR gun.

 

[J-FRAME]

A fun project. I had a very nice 4 inch m 48 back in the day nice target grips target hammer and trigger. The muzzle blast was excessive. Sometimes you have no hearing protection handy and need to use your gun. Very hard on the ears Kept my m18 sold the m 48. Had other handguns in 22 magnum. It really is a rifle cartridge just my two cents

 

[austintexas]

In 1964 I picked up a Stevens Favorite .22 ($3.50), asked the local gunsmith about converting to 22 mag (not a lot of 22 mags around then). He told me he had one that he converted for himself. So, for $10.00 he re-chambered a used .22 marlin barrel, fit it, drilled and tapped the barrel for scope mounts. All he did to the receiver was modify the extractor. I've been shooting this gun for almost 60 years.
Just a note: Sept 1964 I was working at Fisher Electronics building stereo equipment for $1.27 an hour. Old and broken guns were cheap as was labor compared to today.
SWCA 892

 

[SuperMan]

Yea...people complain that guns are so expensive... In 1968 I was making a $1.65 working in a grocery store during high school... In 1968 a S&W Model 19 was $120.00...

Today a kid in a grocery store makes 7-10X that and one can buy a S&W .357 under a grand...

 

[Muley Gil]

I added an extra stainless .22 LR cylinder (drop-in fit) to my stainless New Model Ruger Bearcat and then re-chambered it to .22 Magnum. It shoots just fine.

 

[350mag]

I purchased a nice 6” M 48-2. A previous owner either lost or sold the 22 mag cylinder. I could not find a blue 22 mag cylinder so I’m in the process of refitting the ejector rod in a new 648 cylinder.


Sent from my iPhone using Tapatalk

 

[wundudnee]

In 1964 I picked up a Stevens Favorite .22 ($3.50), asked the local gunsmith about converting to 22 mag (not a lot of 22 mags around then). He told me he had one that he converted for himself. So, for $10.00 he re-chambered a used .22 marlin barrel, fit it, drilled and tapped the barrel for scope mounts. All he did to the receiver was modify the extractor. I've been shooting this gun for almost 60 years.
Just a note: Sept 1964 I was working at Fisher Electronics building stereo equipment for $1.27 an hour. Old and broken guns were cheap as was labor compared to today.
SWCA 892

Also in the 60s I bought an 1890 Winchester from a local gun smith. It had two different serial numbers and had a Marlin barrel chambered in S. L, LR.
He had chambered it to the original WRF. He was adamant that I understood the difference between .22WRF and .22 LR. I gave him $12.50 for that rifle and carried it in the truck for years. It seemed to be exceptionally accurate.
I wouldn't worry about installing a .22 Mag cylinder in a .22 LR revolver.

 

[S.B.]

I got a bug in my butt a while back and purchased a stainless steel cylinder from Numeric in .22 WFM then sent my 617 to Andy Horvath in Ohio to have it all fitted together. Now, I can change from Lr to magnum with just a screw driver. Andy does great work!
Steve

 

[wagwan]

I love these projects! Could some of you guys post pictures / info on the reamers that you used for the conversion? Are there differences in rifle vs revolver reamers for 22 mag?