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Old March 28, 2010, 03:10 PM   #1
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22LR to 22RFMag, Convertion?

I have an old 22RF rifle that I would like to convect. Has anyone slugged a 22RF barrel and compared it to a 22RF Mag barrel? Over the years, I have lost the mags and I was planning to use this conversion as a single shot.
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Old March 28, 2010, 04:44 PM   #2
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This question seems to pop up regularly, but I don't recall any iron-clad answers. Just went and checked some Federal .22 mags and .22LR in the shop and here's what I found: the mag and the LR had the same diameter projectile, but the mag had a jacket, so concievably could be slightly higher pressure to push it down the barrel. The LR case rim was .271 inches and the mag case was .287 inches, didn't compare the length so you might have a fit problem in the action. I wouldn't do it, but that's just me. Here endeth the epistle. Goatwhiskers the Elder
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Old March 28, 2010, 04:55 PM   #3
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The main difference is the .22 CB and BB caps and the Short, Long, and Long Rifle bullets are heeled, meaning they narrow behind the bullet bearing surface so the case can be the same diameter as the widest part of the bullet. The .22 Mag and .22 WRF both use a straight sided bullets and the cases goes over them, so the case is wider than the bullet, like with a centerfire straight wall cartridge case, and so the case is wider than the .22 rounds mentioned in the first sentence. A number of revolvers have had conversion cylinders over the years, so the bullet and bore fit are not the issue.

With the mag and WRF cases wider, you need someone with the right chamber reamer to rechamber the barrel for either one. The WRF has a 45 grain lead bullet and is loaded to lower velocities if you are wanting something that's a little less of a jump, but their harder to find. The difference isn't large enough so a firing pin located for the .22 LR would have trouble firing the Magnum or WRF in any instance I'm aware of? The extra four thousandths of radius at the rim, though not a big difference, may make extractor fit too tight in some actions. That could take a bit of attention to sort out, but nothing herculean by way of effort.

Some .22 RF barrels are awfully soft. That and the extra pressure and powder may combine to cause accelerated throat wear if you use it a lot with the magnums. But as a single shot, you probably won't use it that much.
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Last edited by Unclenick; March 28, 2010 at 05:00 PM.
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Old March 28, 2010, 06:14 PM   #4
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Rimfire barrels measure .223 and the 22 RF magnum barrels measure .224, you will be pushing a over size bullet down a smaller hole and as said before the barrel steel is not the same.
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Old March 28, 2010, 06:53 PM   #5
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I have an old 22RF rifle that I would like to convect
From reading this, I get the impression that you have a 22 WRF and want to convert it to 22 WRM. Is this right? If so, you just need to ream the chamber to 22 WRM dimensions.

If instead the rifle is chambered for 22 Short, Long, or Long Rifle, I would recommend you find a different project. 22LR has a smaller bore than the 22 WRM, which will cause pressure issues.

22LR and 22 WRM share the same SAAMI max pressure rating, 24,000 psi.
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Old March 28, 2010, 07:37 PM   #6
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Besides, the firing pin of a .22LR firearm may not be of sufficient width, or in the correct position, to reach/ignite the priming compound in the rim of the larger cartridge.

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Old March 28, 2010, 10:29 PM   #7
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If you just want a project to do, consider a barrel liner in .17 caliber. Around my area it is becoming the popular thing to do, even to the Magnums. The .22 Magnum is going to fade away in the future so why waste the time and money?
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Old March 28, 2010, 11:28 PM   #8
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The old gun may not hold up for long under the extra pressure of the 22 mag round. You do not want to be picking pieces of the colt or action out of your face. Have seen several older 22's that have been converted to 22 mag, and it was when the owner or a lawyer wanted to sue the manufacturer after the gun came apart. Your gun might be strong enough and never have a problem, but is it worth risking an eye or two?
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Old April 8, 2010, 04:32 AM   #9
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Well I did it, and it worked out prefect. In fact, I shot a 2 inch group at 50 yds (22LR), using the iron sights before the conversion, and afterwords I shot a 1 inch group at 50 yds with the 22Mag. I tied it to a tire and shot 10 rounds thur it as fast as I could. No problem. No miss fires. No nothings.
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Old April 8, 2010, 12:49 PM   #10
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Glad things worked out for you.

Is there a reason for us to not know what kind of "old .22" you started with?
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Old April 8, 2010, 02:33 PM   #11
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Sorry, its a French made army training rifle called MAS 45. It was one of many genetic surplus rifles that hit the market back in the '80's...
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Last edited by Bones; April 8, 2010 at 03:52 PM.
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Old April 8, 2010, 06:26 PM   #12
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I don't know about French training rifles, but I suggest re-reading Unclenick's last paragraph. The rifling in many of those old .22 barrels can last less than 200 rounds with the high velocity jacketed bullets of the .22 WMR.

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