.22LR to .22WMR conversion?


September 21, 2004, 03:17 PM
Hi all,

I have a Sharps in .22LR, the bore is .223" and the lands are at .218" (info from Sharps). It's seen maybe 1,200 rounds of yellow jackets through it. I'm thinking of having the barrel removed and have a gunsmith rechamber the throat to accept the .22WMR. I believe the 22mag barrels are bored at .224". If I also have a gunsmith hand lap a thousandth off the barrel bore will I get great accuracy (theoretically)? I ask cuz my bore will be .001" closer to the lands. Also, I don't want to unnecessarily raise the pressure with the "oversized" bullet by not having the barrel opened at all.

(I know about the convertible Ruger single-sixes; I think they were chambered at the factory for the 22mag, though, so I don't think an accuracy comparison is valid, even allowing for their being handguns).

Thanks for your thoughts,


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Jim Watson
September 21, 2004, 05:01 PM
You have a SHARPS .22?
Is it one of the Li'l Sharps or is it a fullsize '74 or '75?

I am not a gunsmith, but it is my opinion that it could be rechambered to .22 magnum. Pressures probably would not be excessive if the chamber were properly cut with release of the bullet into the leade. As P.O. Ackley said, the bullet will be sized to fit the barrel by the time it has traveled its own length, which will be before pressures are at the maximum anyhow.

I don't know if you could lap out a full thousandth evenly enough to preserve accuracy. I don't think magnums are as inherently accurate as long rifles at their best. What is the change FOR?

September 21, 2004, 05:54 PM
Hi, Jim,

Thanks for answering. I just don't know enough about ballistics. I thought in "the old days" the "best" barrels were hand-lapped. Since the difference is "only" a thousandth, I was thinking that any amount of metal that was taken off would help ease this "oversize" bullet along. Also, Beartooth recommends "fire-lapping" their bores to smooth constrictions, etc.

But, I confess that I don't really understand this well, cuz, for instance, in 44mag, shooting 1 or 2 thousandths over is not a problem, and to hear some "oversize" bullet manufacturers and reading other posters, it's actually more accurate to shoot an "oversized" bullet. BTW, I do shoot .358" 357s and .431" 44s, have no problems, less barrel leading, and see really reasonable accuracy.

However, the gunsmith I talked to who would do the work was concerned that if we (he) didn't open the bore a little, that the pressure might be too much.

Yeah, I know, why would anyone buy a Sharps in .22LR...? But, I did. Yes, it's a C. Sharps 1875 with a 21" bbl. Why the change? It's been up for sale for ~ 6 mos- no bites. I'm bored shooting it- since it won't sell for a reasonable price (for a Sharps) I'm thinking that if I turned it into a 22 magnum, it would be more "useful"; I could shoot well out to ~125-150 yds and I could use it for targets @ 100yds and varmints, etc at the longer distance with the 50gr Federal load (~175-180 ft/lbs @ 100yds; 140-145 ft/lbs @ 150yds). I don't shoot varmints (honestly) but I also don't want any "useless" guns around....


September 22, 2004, 08:51 AM
You could install a liner if you are worried about it. For that matter, you could reline the barrel to .17 HMR. That might help with your boredom!


September 22, 2004, 01:36 PM
Hi Clemson,

Thanks for your thoughts. I thought about the .17HMR, but the (for instance) Federal 757 .22mag load has lots more downrange energy for hitting spinners, jugs, gongs, and, alas, varmints. I believe the .17HMR shoots flatter, but I don't mind a little arch in my trajectory. .45-70 shooters deal with that and wind drift all the time.

The idea of a liner is intriguing. What's involved with installing a liner? Do we just bore out the barrel I've got and shove in a sleeve (liner)? So I could reline the barrel over and over again in the future? Is this as good as what I've got as far as barrel life and accuracy are concerned?

It seems from your words that you would not be worried about shooting .001" over bullets, as long as the chamber were reamed to seat the longer mag cartridge- is that true? Am I worried about nothing here? :)



Old Fuff
September 22, 2004, 01:46 PM
The problem in any rim-fire is that they have weak heads. The cases are folded out of sheet stock, where C.F. cartridges have solid heads. If your conversion results in increased-over-normal pressure you could experience blown heads. A lot could depend on who did the work.

Ruger Single Six series revolvers are barreled to Magnum-bore specifications, and therefore slightly oversized for the regular rim-fire cartridges.

September 22, 2004, 02:02 PM
Brownells sells the same liner for both .22 L.R. and .22 Magnum. It is sized with a .223 groove diameter according to Brownells. I would be more comfortable with using one of those liners than with chancing higher pressures if rechambering your existing barrel. To install one you use a piloted drill (also available from Brownells) and either soft solder or Accraglass the liner in place. Dress off the ends of the barrel, cut the chamber with a reamer, cut whatever extractor recess is required, and you are good to go. It would be nice to have access to a lathe, particularly for crowning, but it could all be done by hand if that is what you have to do.

As Old Fuff quite correctly pointed out, your action must be in good condition and strong enough to withstand the higher pressure of the magnum rounds. Look at it from the point of view of handling gas escapes, too.


September 22, 2004, 02:04 PM
Hi 1x2,

I always thought 22LR bullets are sized at .221" and 22WMR bullets are .223", just like 22 Hornet bullets, while 223 Remington and other centerfire 22 bullets are sized at .224" . I think you need to verify the bore dimensions before looking into relining. I think all you need is to rechamber it to 22 Mag is a reamer.


September 22, 2004, 04:03 PM
Wow! This is fabulous assistance! Thank you all for taking the time to share your thoughts and ideas process knowledge. (No joke, the company's great, I really appreciate it).

I called Sharps on the phone, the customer service rep said she had to go out back and ask a tech to verify the dimensions, the .223 bore and .218 lands are what she came back with- so I believe she meant the grooves are .223 and the lands are .218.

I just called them back and talked to a tech "out back"; his take is that the LR bullet is ~.223, the magnum bullet is ~.224. He said the bore (groove) dia. for LR is ~.223 and the mag is ~.224. (When reading up on the 22 Hornet after I got off the phone (a chambering which Sharps also offers in that rifle) at www.reloadbench.com the article states that 'the .223" 22 Hornet bullet was adapted from the 22LR rifle and used in a particular Springfield rifle as that rifle had a .223 bore to match', which indicates that they were all the same dia.).

The Sharps tech further said that the current barrel would be tight for the magnum bullet, and the pressure would be higher, but the action is a falling block and is the same action used on all their rifles so it's more than plenty stout for a .22 rimfire. (I read somewhere that the pressure for a 22LR is ~24,000 psi). It's his opinion that accuracy would be about the same as through any other magnum rifle, which accuracy is not as good, generally, as the .22LR.

This info dovetails with the Brownell's offering of the same liner for WMR and LR at .223". The magnum would be tight and they caution on their site that the liner should be used only on LR rifles or WMR rifles that were originally chambered for WMR- I'm thinking that's due to the increased pressure a magnum has over the LR and the tightness of the barrel.

So, apparently I can just have the chamber reamed on the barrel now on the gun to seat the magnum cartridge, file the extractor "tab" and voila! a more powerful, less accurate .22 rifle... but how bad would that be? The 22 magnum can't be "inately inaccurate" or who would buy them?

Thank you all for your help! :)


Old Fuff
September 22, 2004, 04:56 PM
Slow down!!!

You missed my point. The problem could be (I said "could be") the cartridge case, not the action. The action is more then strong enough, but if the rim is not fully enclosed, and if the headspace is not very tight, you "could" get head seperations that would leave the rest of the case in the chamber. Getting that out "could" be a major pain in the you know what. If the chambering and headspacing is done carefully you will probably be O.K. If not, it would likely be "new barrel time" with all the expense that involves.

Since (as I understand it) there is nothing wrong with your .22 R.F. barrel I would remove it, have a new "correct" barrel chambered in .22 WRM, and then mounted. Then you'd have the option of going back if for whatever reason the Magnum didn't work as well as you expected. If it did you could sell or trade off the .22 R.F. barrel. Never be too quick to burn a bridge.

September 22, 2004, 05:55 PM
Sounds like the barrel is a OK to use, provided a competent gunsmith does the rechambering. With luck, recutting the chamber with a 22 WMR reamer while checking the headspace should yield the results you desire. Worst case the chamber end of the barrel would have to be cut back one turn and the chamber recut, if the headspace was excessive.

Have fun,

Jim K
September 22, 2004, 10:58 PM
I think you folks are worrying about the wrong thing. I would worry less about .001" barrel diameter than about the barrel steel. Barrels made for the .22 LR are usually made from fairly soft steel and it doesn't take many rounds of .22 WMR to wipe them out.


September 23, 2004, 11:07 AM

Thanks for answering. C. Sharps was using Badger barrels exclusively when this was made (have no idea what they're using now), so it should be ok- I don't have it handy for measurements (it's in a display case for sale at a dealer) but it is the SAME barrel blank they use for all their rifles- and with only a .223" hole in it, there's a lot of steel left! It sure wouldn't bother me to honestly wear this one out, then I'd have a good excuse for a new, lighter weight bbl.

Old Fluff,

So your point was to caution me to have a GOOD gunsmith ream the chamber and watch the length/fit and headspace carefully? I got it, thank you for the pointer. BTW, if there was a market for heavy octagonal bbls I'd consider removing and selling it (as I've not shot it in several years, and don't care to, in .22LR). So I'd like to use the bbl I've got, since I don't think anyone else would want it. This thing is a money sink (check their wesite)! :D

(All this is second best to having it rebarreled to 44magnum, but changing from RF to CF would be a costly undertaking, so, where the 22mag isn't any more expensive to shoot than reloads, the 22mag gets the nod- if it'll work....)



September 23, 2004, 11:08 AM
Sorry, dup posting, could not delete... 1x2

September 23, 2004, 01:37 PM
Two things here.

Old Fuff, you wrote

Ruger Single Six series revolvers are barreled to Magnum-bore specifications, and therefore slightly oversized for the regular rim-fire cartridges.

Huh, interesting! I had it filed in the back of my dusty head the other way 'round...

1x2, you wrote:

So your point was to caution me to have a GOOD gunsmith ream the chamber and watch the length/fit and headspace carefully? I got it

No, you're not getting it. The point is that when you send a jacketed bullet down a slightly undersized bore, pressure swaging it, the presure will be higher than intended by the manufacturer of the brass case.

.22 RF brass, including .22 WMR, is thin, balloon-head construction. A case head could easily let go. This may not (or may) damage the rifle -- the barrel and action may be more than strong enough to contain the pressure.

However, venting the hot gas backwards through the action into the immediate area of your face could result in serious physical injury. None of us here probably has a clue how the falling block action vents gas, but I'll bet there's a good chance that a good percentage will come straight back around the block.

The cartridge case is a weak link. Think about it -- part of the function of the case head is to act as a seal when a gun fires. If the seal lets go, you have an unintended consequence.

Jim K
October 1, 2004, 10:50 PM
Hi, JNewell,

I agree with what you say, although I don't think a barrel .001 undersize is a big problem, and BTW, Ruger convertible barrels are sized for the .22 WMR bullet.

But permit me one point on terminology. A balloon head case is not a rimfire case. A balloon head case is a center fire case whose head inside the case is thin between the pocket for the primer and the side of the case wall. If you look inside the case you can see the primer pocket sticking up above the rest of the base. Solid head cases (the norm today) are the same thickness all the way across the base inside the case. The base is the same thickness all the way across, and if you look inside you see only the flash hole in a flat base.

The only concern is in reloading. There are still some balloon head cases made and they are fine for reloading with standard loads, but solid head cases should be used for "hot" loads.


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