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 Rechambering .22 LR to .22 Magnum
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Isher2000
Starting Member

USA
34 Posts

Posted - 09/17/2013 :  11:56:06 AM  Show Profile
I've noticed a few used guns on sale recently that have their chambers opened up from .22 LR to .22 Magnum. The ones I've seen included a Contender pistol barrel and an S&W J-Frame revolver.

Any opinions on the safety and/or usefulness of this practice?

Any known ammo type incompatibilities?

Thanks

rufe-snow
Advanced Member

15851 Posts

Posted - 09/17/2013 :  12:23:55 PM  Show Profile
The OD of the .22 mag cartridge is approximately .015 larger than the .22 LR. It obviously has a higher operating pressure than .22 LR.

I can see rechambering a Contender barrel to .22 Mag. But IMHO your pushing your luck in rechambering a "J" frame Smith.

Years ago I ruined a Model 37 by shooting my handloads in it. My feeling is a steady diet of 22 mags. Would probably do the same to a Model 34 rechambered to 22 mag.

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tsr1965
Advanced Member

USA
7123 Posts

Posted - 09/17/2013 :  12:32:35 PM  Show Profile
Most of the 22 caliber barrels, and I'm going out on a limb here, but most of them are the 0.224 diameter and not the smaller diameter of the older heeled 22 LR bullet. That said, the j-frame, considering a newer all steel one, no alloy would take it, and a Contender/ Encore, deifnately would handle it.

Taurus, even makes/made the 941 ultra lite in 22WMR, if memory serves me.

rufe, if memory serves me, was not that model 37 an alloy frame? Anyway, there is a lot of difference in the diameter of the 22 WMR rim, and the 38 rim, as far as thrust is concerned. I have seen several alloy j-frames, shot out of service by lots of shooting.

Best

Take a look at these auctions on the otherside...
http://www.GunBroker.com/Auction/BrowseItems.aspx?IncludeSellers=484399


Edited by - tsr1965 on 09/17/2013 12:32:58 PM
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Isher2000
Starting Member

USA
34 Posts

Posted - 09/17/2013 :  12:40:41 PM  Show Profile
Thanks for the replies.

I did worry more about the J-Frame from a safety standpoint. After all you can shoot .45-70 and .35 Remington in Contenders safely. Though I'm not sure I would want to do that more than a couple of times.

Would rechambering the Contender be technically difficult? Revolver cylinders present a smooth freebore in front of the chamber. Rechambering the Contender barrel might run into the start of the rifling.
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dfletcher
Advanced Member

USA
6521 Posts

Posted - 09/17/2013 :  2:42:03 PM  Show Profile
quote:
Originally posted by Isher2000

Thanks for the replies.

I did worry more about the J-Frame from a safety standpoint. After all you can shoot .45-70 and .35 Remington in Contenders safely. Though I'm not sure I would want to do that more than a couple of times.

Would rechambering the Contender be technically difficult? Revolver cylinders present a smooth freebore in front of the chamber. Rechambering the Contender barrel might run into the start of the rifling.



Rechambering a Contender from 22 lr to 22 WMR would be pretty straightforward. I've seen cost quotes on rechambering of centerfires from $90.00 to $150.00. I don't know if Match Grade Machine does rechambering, you might contact them and ask.

Regarding touching off a few rounds of 35 Remington and 45/70 in the Contender - great fun. Full bore reloads in the 45/70 are pretty stiff. I use an Encore pistol in 375 H & H, 405 Winchester & 350 Rem Mag and the 45/70 recoil beats them all.


dsf
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beantownshootah
Advanced Member

USA
13157 Posts

Posted - 09/17/2013 :  2:52:39 PM  Show Profile
quote:
Originally posted by Isher2000

Thanks for the replies.

I did worry more about the J-Frame from a safety standpoint. After all you can shoot .45-70 and .35 Remington in Contenders safely. Though I'm not sure I would want to do that more than a couple of times.

Would rechambering the Contender be technically difficult? Revolver cylinders present a smooth freebore in front of the chamber. Rechambering the Contender barrel might run into the start of the rifling.


First of all, Smith makes (or made) a J frame in .22 magnum, eg the 351PD model, and its an aluminum alloy frame model. So its not like J-frames aren't strong enough to handle .22 magnum rounds. Clearly, they are.

More to the point, J-frames have also been chambered in both 9mm luger and .357 magnum, each of which operates at FAR higher pressures than any .22 magnum, plus of course, the .22 magnum cylinder has a lot more steel around it [edit, I mean a lot more steel around each cartridge hole] than the much larger centerfire pistol rounds, which should make the cylinder that much stronger yet.

Both .22LR AND .22 magnum operates at the same exact SAAMI max chamber pressure of 24,000PSI, by the way, so a gun frame or cylinder strong enough for one should be strong enough for the other.

So, IMO, operating pressure isn't really an issue here. Any non-defective revolver from a "name" manufacturer ought to be more than strong enough to handle .22 magnum pressure. The big issue, IMO is slightly increased bullet diameter of .22 magnum. That plus increased powder might wear out .22LR barrels faster and/or decrease accuracy with WMR (though maybe accuracy is irrelevant from a snubnose pistol anyway).

More important, I really don't see the point of this particular conversion, at least not with a snubnose revolver.

.22 magnum is a *RIFLE* round, and it gets its increased velocity by using a lot of slow-burning powder, most of which is wasted in a short pistol barrel, creating a large flash of unburned powder, instead of kinetic energy in a faster bullet.

If you take a look at the ballistics, .22 magnum from a 2" barrel or less only does a tiny bit faster than .22LR from the same barrel length. In my opinion, that makes .22WMR a poor choice for these sorts of platforms.

Edited by - beantownshootah on 09/17/2013 2:54:58 PM
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rufe-snow
Advanced Member

15851 Posts

Posted - 09/17/2013 :  3:07:39 PM  Show Profile
quote:
Originally posted by beantownshootah


If you take a look at the ballistics, .22 magnum from a 2" barrel or less only does a tiny bit faster than .22LR from the same barrel length. In my opinion, that makes .22WMR a poor choice for these sorts of platforms.



Up until a couple of months ago, I would have been in total agreement, with you. In the American Rifleman's June 2013, issue though. An article was published giving 22 mag velocities from NAA 1.8" barreled revolver. They ranged from 1062 to 1252 FPS. This surprised the heck out of me. As I believe that would be a good 200 FPS faster than a .22 LR, from the same length barrel.

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Ray B
Advanced Member

9343 Posts

Posted - 09/17/2013 :  3:49:38 PM  Show Profile
I don't know what the bore diameter was, but I recall that the Ruger Single Six Convertible revolver barrel diameter was larger to accommodate the 22WMRF than the models that were for 22LR only.
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beantownshootah
Advanced Member

USA
13157 Posts

Posted - 09/17/2013 :  3:59:48 PM  Show Profile
quote:
Originally posted by rufe-snow
quote:
Originally posted by beantownshootah


If you take a look at the ballistics, .22 magnum from a 2" barrel or less only does a tiny bit faster than .22LR from the same barrel length. In my opinion, that makes .22WMR a poor choice for these sorts of platforms.

Up until a couple of months ago, I would have been in total agreement, with you. In the American Rifleman's June 2013, issue though. An article was published giving 22 mag velocities from NAA 1.8" barreled revolver. They ranged from 1062 to 1252 FPS. This surprised the heck out of me. As I believe that would be a good 200 FPS faster than a .22 LR, from the same length barrel.

In absolute terms, that's faster than I remember, but the faster velocities you're citing come from lightweight 30 grain bullets (not ordinary 40 grain ones).

Unfortunately, NAA took down its very handy published comparison chart, where it listed chronographed ballistics through all its guns with a variety of real ammo, so I can't give you a link to good apples-to-apples comparisons.

But if you look at available data, the .22 magnums do about 10% better than .22LR from the 2" bbls and the difference actually goes down as the barrels get shorter.

As one reference, BBTI lists 1085 FPS muzzle velocity for the CCI 30 grain V+ round, and 974 FPS for the .22LR 32 grain CCI Stinger, each with 2" bbls. So that's about an 11% velocity edge for the .22 magnum.

In the same test, the various 40 grain 22 magnums get about 890 fps from 2" bbls. Meanwhile the premium 40 grain .22LRs (CCI mini mag, Winchester Super X, and CCI Velocitors) get 850-880 fps, almost the exact same velocity.

BBTI, doesn't go down that low, but once you get down to 1" bbl velocities with the 40 grain .22 magnum bullets are still pretty anemic, only about 875 fps:

http://naaminis.blogspot.com/2010/08/north-american-arms-pug-ballistics.html

And in fact, if you check the above chronographed data with a 1" bbl, one of the 31 grain .22LR bullets tested (The Federal "spitfire") actually outperforms all of the .22 magnum rounds!

If you consider that the case length of a .22magnum is about 1/2" longer than the .22LR, you can squeeze in another 1/2" bbl length in a .22LR gun for same overall gun size, further reducing performance difference in these short wheelguns.

Bottom line, is yes, the .22 magnums do a *little* better than .22LR, from really short barrels, but if you factor in significantly increased ammo cost, increased noise, and significantly increased muzzle flash, I'm not sure the small ballistic advantage outweighs the other disadvantages. Bluntly ANY .22 caliber 30-40 grain projectile only doing 850 fps isn't going to carry a lot of stopping power. A few fps either way is going to be far less important than simple placement, and some of that is going to be dumb luck (eg does your bullet hit a rib on the way in or not?).

Lastly (and probably most important), if you're going to carry a 1-7/8" J-frame, why on earth are you going to carry one in .22 magnum when these are just as available in .38+P?
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62fuelie
Member

USA
717 Posts

Posted - 09/17/2013 :  5:18:25 PM  Show Profile
If the barrel of the J-frame is the smaller bore then you should be getting added stress at the front of the top frame strap and run the risk of stretching it when you run a larger jacketed bullet into the forcing cone.

B
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62fuelie
Member

USA
717 Posts

Posted - 09/17/2013 :  5:18:32 PM  Show Profile
If the barrel of the J-frame is the smaller bore then you should be getting added stress at the front of the top frame strap and run the risk of stretching it when you run a larger jacketed bullet into the forcing cone.

B
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Riomouse911
Advanced Member

USA
2872 Posts

Posted - 09/17/2013 :  5:54:31 PM  Show Profile
Here is a real test of ballistics from several cartridges with various barrel lengths:

http://www.ballisticsbytheinch.com/calibers.html.

Whether it is worth the effort rechambering a S&W .22lr snub to .22 WMR is your decision. I have a 4" Taurus 94 in .22lr and a 4" .22 WMR 941..and the WMR does make more boom and seems to hit the steel plates a tad harder than the LR...from a 2" barrel? I dunno.
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TANK78Z
Member

USA
741 Posts

Posted - 09/17/2013 :  7:38:04 PM  Show Profile
Back in the early 80's I Used a reamer set to open up the cylinder of several model 34's to accept 22 mags.
Never had any complaints or problems with any of them.
One was my own blued 2.5", I still have it and shoot it several times a year, maybe a total of 200/250 rounds in a year.
After 30 years of use it is still going strong, Except for possibly lowering its resale value I really don't see a problem in converting a newer one.

"No man is above the law, and no man is below it, nor do we ask any man's permission when we ask him to obey it." Teddy Roosevelt
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