Rechambering an H&R 929 from 22 Long Rifle to 22 WMR

[sean m]

Recently picked up a second cylinder for an H&R 929 in 22LR and was thinking about having it rechambered for 22 WMR. Has anyone done this before, or ran into any issues?

 

[beag_nut]

Have you checked to see whether the cylinder is long enough for the WMR? This is not what I would call a desirable mod for the pistol, especially since it is a H&R.

 

[Catpop]

Imho, no. It might fit, but it may not hold the pressure.

 

[someguy2800]

22 mag and 22lr have the same sami chamber pressure of 24,000 psi. If the cylinder is long enough it will be fine. I really can't see taking out the .008" difference in cylinder thickness causing a problem

 

[CraigC]

Yep, pressure is the same, .22Mag just has more, slower burning powder.

 

[chicharrones]

If the cylinder as long enough and you like the bigger bang, I'd try it too. Ammo is going to cost a lot more though.

One time I thought about doing the same mod to my H&R 999, but the cylinder is much too short. So, that ended that thought experiment rather quickly.

I still have thoughts about modding a Ruger Bearcat to .22 Mag, but I'd have to own a Bearcat first.

 

[Acera]

I like the idea.

That will be one loud revolver when finished.



.

 

[ironworkerwill]

Bad idea...... probably. If was a variant was made in both .22lr and .22WMR then it "might be ok" if the chamber length is ok.

But you'll really need to check the bore diameter or you may burst the case heads due to over pressure. The actual bore dimensions are supposed to be different. Some manufactures that shoot the LR and WMR through the same frame probably use the WMR spec barrel for both to avoid pressure issues.

.22lr should have a .217 bore and .22WMR should have .219 bore as the bullet diameters are different!

 

[chicharrones]

But you'll really need to check the bore diameter or you may burst the case heads due to over pressure. The actual bore dimensions are supposed to be different. Some manufactures that shoot the LR and WMR through the same frame probably use the WMR spec barrel for both to avoid pressure issues.

.22lr should have a .217 bore and .22WMR should have .219 bore as the bullet diameters are different!

Wouldn't any over pressure due to a .002" smaller barrel bore blow out of the cylinder gap?

 

[chicharrones]

Since this sparked my interest in a .22 Mag Bearcat again, I was looking through a couple of sources on the subject. It looks like the larger diameter of the .22 mag cartridge might run into problems with a firing pin located for the smaller diameter .22 LR cartridge. Being a rimfire, this may be kinda important.
http://www.gunblast.com/Boge_BowenBearcat.htm
http://www.clementscustomguns.com/bearcat.html

I remember the reason that finally killed my idea of a barrel .22 Magnum gun. Muzzle velocity wasn't improved enough over a .22 LR, IMO. I figure if I wanted a loud rimfire snubnose class revolver, I'd just load it with CCI Stingers. My old Beretta Bobcat is an ear piercer with Stingers.
http://ballisticsbytheinch.com/22mag.html
http://ballisticsbytheinch.com/22.html

 

[ironworkerwill]

Wouldn't any over pressure due to a .002" smaller barrel bore blow out of the cylinder gap?

I can't tell you what I don't know. Maybe, maybe not. There is only one way to find out.

 

[Jim K]

I wouldn't worry a lot about strength, but the .22 WMR case is stronger and harder than the .22 LR and the gun might not fire the .22 WMR.

Jim

 

[CraigC]

Bad idea...... probably. If was a variant was made in both .22lr and .22WMR then it "might be ok" if the chamber length is ok.

But you'll really need to check the bore diameter or you may burst the case heads due to over pressure. The actual bore dimensions are supposed to be different. Some manufactures that shoot the LR and WMR through the same frame probably use the WMR spec barrel for both to avoid pressure issues.

.22lr should have a .217 bore and .22WMR should have .219 bore as the bullet diameters are different!

Bore diameter is a non-issue and in a revolver it has no bearing on chamber pressure.

 

[ironworkerwill]

Bore diameter is a non-issue and in a revolver it has no bearing on chamber pressure.

I wouldn't know. But I suppose anything is possible. However, I'm a not comfortable or confident in stating that the pressure will be relieved enough to prevent any issues.

 

[CraigC]

I wouldn't know. But I suppose anything is possible. However, I'm a not comfortable or confident in stating that the pressure will be relieved enough to prevent any issues.

If you don't know one way or another, why comment on it at all?

By contrast, I do know, which is why I posted. Not only can the difference between the two fall within manufacturing tolerances between individual guns, it ain't much to begin with. Coupled with the fact that a good many Ruger Bearcats have been rechambered to .22Mag by nationally recognized gunsmiths. I even got a quote from Clark Custom Guns several years ago on converting a K-22 to .22Mag. All of which adds up to a non-issue.

 

[ironworkerwill]

If you don't know one way or another, why comment on it at all?

By contrast, I do know, which is why I posted. Not only can the difference between the two fall within manufacturing tolerances between individual guns, it ain't much to begin with. Coupled with the fact that a good many Ruger Bearcats have been rechambered to .22Mag by nationally recognized gunsmiths. I even got a quote from Clark Custom Guns several years ago on converting a K-22 to .22Mag. All of which adds up to a non-issue.

Because it's a safety issue. I am unable to make any measurements on the weapon to insure that the bullet will pass through the cylinder gap entirely without producing enough pressure to rupture the case head.

If you're sure then you should be the guinea pig. Maybe nothing will happen.

I rechambered a 22lr to 22mag and had ruptured case heads this is why I know it can happen. With someone's hands near an unsupported head if it did rupture it could possibly cause a chainfire as bits of brass strike the rims of the other rounds in the cylinder.

You posted as a reply to my comment and I reposted my concern.

The fact is, you really don't know what will happen any more than I do.

 

[CraigC]

You do realize that gunsmiths are tasked with figuring all this out, right? They don't just blindly do what the customer asks.

If there was a risk of chainfire, then they wouldn't now be building rimfire revolvers without recessed heads.

I'd be curious as to why yours was rupturing case heads.

 

[ironworkerwill]

Indeed, a competent person should know the difference.

My case was single shot rifle both times. The first was a single shot Springfield that worked great the second was a Cricket. Both rifles supported most of the heads. We concluded the Cricket had ruptured heads due to the more constrictive bore.

 

[chicharrones]

Okay, but we are talking rimfire revolvers here and most modern rimfire revolvers have the cartridges nearly fully supported. Plus, there is very little space behind the fired cartridge where it is supported in front of the firing pin. So little space in many cases that chamber or ejector fouling will cause a newly loaded cartridge to drag on the frame of the gun in front of the firing pin.

With a bolt gun or a semi-auto there may be cuts for an extractor(s) or feed ramp at the chamber that can leave a cartridge partly unsupported. For instance my old Beretta Bobcat will form a bulge in the brass in the shape of the feed ramp when firing CCI Stingers. Where my H&R 999 revolver will not deform the brass when firing Stingers.

My biggest worry about a .22 LR re-chambered to .22 Magnum (with a modern cut cylinder) would be perhaps flame cutting of the frame above the cylinder gap. But I have yet to see that in steel framed .22 magnum revolvers.

 

[chicharrones]

Since this thread started off about the H&R 929, none of this may matter as I suspect the cylinder may be the same length as a 999 cylinder. Which would mean a .22 WMR would be too long for that cylinder.

Yet, for cylinders that are long enough, below are some examples of .22 LR and .22 WMR cylinders and the cartridge support they offer. Sometimes even the rim itself is supported like in the Ruger Single Six series of guns. But for those cylinders without rim support, the cylinder itself usually has an outer "safety ring" around the circumference of the back of the cylinder.

All seen at Gunblast, so links instead of photos.

NAA Earl cylinders (.22LR/.22WMR) - http://www.gunblast.com/images/NAA-Earl/DSC07426.JPG
Link to web page - http://www.gunblast.com/NAA-Earl.htm

Taurus Tracker cylinders (.22LR/.22WMR) - http://www.gunblast.com/images/Taurus-992Tracker/DSC02791.JPG
Link to web page - http://www.gunblast.com/Taurus-992Tracker.htm

A customized Ruger Bearcat with one cylinder re-chambered to .22 WMR - http://www.gunblast.com/images/Boge_BowenBearcat/DSC01863.jpg
Link to web page - http://www.gunblast.com/Boge_BowenBearcat.htm

I still really like the idea of a .22 WMR Bearcat, even though I'd be better off just firing Stingers out of a .22 LR Bearcat if all I want is the increased noise without the expense of a modified revolver.

 

[walnut1704]

I don't know why not. It's not like H&R didn't make basically the same gun as a convertible. Google the H&R 666.

 

[CraigC]

My case was single shot rifle both times.

Apples and oranges.

 

[Monac]

To me, walnut1704 has the right answer. The H&R Model 666 had the same frame as the OP's and was chambered in 22 Magnum - but as a six shot gun, not a 9 shot. H&R's business was selling revolvers; if they could have made the 666 as a 9-shot, they would have, since having 3 more shots would have helped sales.

Also, I find it hard to picture a gunsmith agreeing to do this job in the first place. Thinning out the chamber walls without reducing the chamber pressure sounds like a bad idea on the face of it. (Unless the gun has massively thick chamber walls, like the old 6-shot J-and-K frame S&W 22 revolvers, of course.)

It also sounds pricey to have done nowadays. Here's a High Standard Sentinel in 22 Magnum that looks about like the OP's 929: http://www.gunbroker.com/item/632979779

It went for $370 plus $35 shipping plus transfer cost, or about $465 or so to take home. Would the work on this H&R cost less?

PS - Case diameter of 22 Long Rifle is .226 inch. Case diameter of 22 Magnum is .242 inch.

 

[chicharrones]

To me, walnut1704 has the right answer. The H&R Model 666 had the same frame as the OP's and was chambered in 22 Magnum - but as a six shot gun, not a 9 shot. H&R's business was selling revolvers; if they could have made the 666 as a 9-shot, they would have, since having 3 more shots would have helped sales.

Also, I find it hard to picture a gunsmith agreeing to do this job in the first place. Thinning out the chamber walls without reducing the chamber pressure sounds like a bad idea on the face of it. (Unless the gun has massively thick chamber walls, like the old 6-shot J-and-K frame S&W 22 revolvers, of course.)

It also sounds pricey to have done nowadays. Here's a High Standard Sentinel in 22 Magnum that looks about like the OP's 929: http://www.gunbroker.com/item/632979779

It went for $370 plus $35 shipping plus transfer cost, or about $465 or so to take home. Would the work on this H&R cost less?

PS - Case diameter of 22 Long Rifle is .226 inch. Case diameter of 22 Magnum is .242 inch.

If the 929 cylinder is like the 999, the chamber to chamber walls are only .050" thick as a .22LR. So, if that's the case with the 929, I agree. I would leave the 929 alone.