9mm revolver conversion


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iyn
April 13, 2011, 02:10 PM
has anyone converted their revolver to take 9mm moon clips? can a modern 38 special revolver handle the 9mm pressures or would you have to convert a .357 mag revolver?

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Lucky Derby
April 13, 2011, 02:58 PM
It has been done, with varying degrees of success.
I would shop for a 9mm revolvers that came from the factory that way.

BCRider
April 13, 2011, 03:20 PM
A .38Spl revolver may not be made with the right cylinder metal to withstand the pressure from a 9mm round. A .357 would be made with steel rated for such pressures.

Then there's the issue of the cylinder needs to be chambered for 9mm. That would require reaming and sleeving. If you only reamed lightly to allow the very slightly fatter 9mm cases to fit then when the bullet leaves the case it would fly unsupported over some distance before entering the smaller bullet sized portion of the cylinder chamber up near the front before then passing through the gap and into the barrel. During that time where it's unsupported between leaving the casing and entering and sealing in the forward portion of the chamber it would be free to tumble and for the propellant gases to bypass the bullet. Both of these factors scream for the cylinder to be reamed and sleeved to produce a better shape of cyinder chamber.

Then the barrel is a couple of thou too big to get a good seal for the bullet and for the bullet to swage into the rifling correctly. So that would require boring and sleeving the barrel to get the most out of such a project gun.

So all in all unless you're fanatical about the idea of a moonclipped 9mm revolver the idea just does not make any sort of financial sense to get there by modifying an existing .357 gun. But if your thinking is "damn the expense" then I sure want to see pictures of the project. I would LOVE to have a moonclipped 9mm revolver in a K frame size.

tekarra
April 13, 2011, 09:11 PM
May I suggest you go to www.smith-wessonforum.com and search. There are a number of posts by people who have have converted K and J frame Smiths to moon clip 9 mm configuration. There is also mention of gunsmiths who do the work, comments on the work and prices.

RidgwayCO
April 13, 2011, 10:08 PM
I'm currently waiting on a S&W M649-3 that is being made into a "convertible" with two cylinders (the original in .357 Magnum, and the extra, fitted, cylinder converted to 9mm Luger). Mark Hartshorn at Pinnacle is doing the work. I'm hoping it will be back home in a couple of weeks or so. Then I'll finally be able to test all those negative possibilities BCRider mentioned.

What I'm expecting is a 5-shot steel J-frame revolver weighing about 23 oz that will allow me to shoot .357 Magnum, .38 Special, and 9mm Luger. For the 9mm I've got a bunch of S&W moonclips designed for their M940, along with a mooning/de-mooning tool. Starline also sent me an e-mail today saying they had shipped my .38 S&W brass. I plan on trimming these down to 0.750" to make them into "9mm Rimmed" cartridges for when I don't feel like messing with the moonclips.

In my head, it could be the perfect system. I'll see if it works out in real life soon enough...

WC145
April 13, 2011, 11:00 PM
As many here are aware, since this subject comes up on a regular basis, I have a S&W 360J that has been rechambered to 9mm (9x23) by Mark Hartshorne at Pinnacle. I wanted a lightweight 9mm snubby and no factory guns met my needs so I had one done up. I've been shooting and carrying my gun for 2.5 years now and I'm as pleased with it today as when I first got it back from the 'smith. It weighs a hair over 13oz, is accurate, superfast to reload, has more power than a .38spl of comparable bullet weight but much less muzzle blast and recoil of a .357mag. Is it perfect? No, there are compromises as I mention below, but the package as a whole works very, very well and, for me, the pros far outweigh the cons.

Anyway, I want to address some of BCRider's points based on my experience.

A .38Spl revolver may not be made with the right cylinder metal to withstand the pressure from a 9mm round. A .357 would be made with steel rated for such pressures.
Per S&W their .38spl and .357mag cyls are made from the same stock, no differences in metallurgy, just chambered differently. These guns and cylinders are stronger than people think. The S&W 940 did not have a special cylinder and it handles 9mm just fine and the 940PC was chambered in 356TSW, which generates pressures similar to the 9x23, around 42k-45k psi, and it used the standard 940 cylinder, the only difference being a slightly deeper chamber.
I have shot standard 9mm, +P, +P+, .38 Super, and 9x23 Winchester through my gun with no ill effects. Generally I train with standard 115gr FMJ, my carry load is 115gr JHP +P+.

Then there's the issue of the cylinder needs to be chambered for 9mm. That would require reaming and sleeving. If you only reamed lightly to allow the very slightly fatter 9mm cases to fit then when the bullet leaves the case it would fly unsupported over some distance before entering the smaller bullet sized portion of the cylinder chamber up near the front before then passing through the gap and into the barrel. During that time where it's unsupported between leaving the casing and entering and sealing in the forward portion of the chamber it would be free to tumble and for the propellant gases to bypass the bullet. Both of these factors scream for the cylinder to be reamed and sleeved to produce a better shape of cyinder chamber.
Yes, the bullet travels through hat 1/2" or so of "freebore" before reaching the forcing cone and some gasses are lost resulting in slightly lower velocities than you get from a revolver properly chambered for 9mm but it is a compromise that comes with one of these conversions. I had the forcing cone of my gun chamfered for a smoother transition from chamber to barrel.

Then the barrel is a couple of thou too big to get a good seal for the bullet and for the bullet to swage into the rifling correctly. So that would require boring and sleeving the barrel to get the most out of such a project gun.
People make way too much of that .002". It's just not enough to make a difference, the bullets catch the rifling and spin true, no key holing, no odd flyers. My gun is as accurate in my hands shooting 9mm as it was shooting .38spl before the conversion. I don't use it for bullseye shooting because that's not what it was made for but I have had no trouble qualifying with it and my scores were within a couple of points of my duty gun, and our course includes shooting out to 25yds.

So all in all unless you're fanatical about the idea of a moonclipped 9mm revolver the idea just does not make any sort of financial sense to get there by modifying an existing .357 gun. But if your thinking is "damn the expense" then I sure want to see pictures of the project. I would LOVE to have a moonclipped 9mm revolver in a K frame size.
So, if you really want a 9mm revolver for self defense use or plinking and the existing factory options don't fill the bill having a gun rechambered is a viable and useful option. Mark charges $225-$275 for the basic conversion depending on the gun and that includes machining the cylinder for moonclips, not cheap but no outrageously expensive either. I had him do other work to my gun so it cost me a bit more than that but as far as I'm concerned it was money well spent.

https://lh6.googleusercontent.com/__3_AZOV0zhc/Sa1aoiSuLTI/AAAAAAAAAYo/pDJSbBroy8g/s800/SDC10436.JPG

iyn
April 14, 2011, 05:53 AM
Thanks wc145. I'm thinking of this conversion so I could have an auto pistol And revolver that shoots the same ammo. I love the moonclips but the N-Frame revolver was too big for my hands and I needed a revolver my wife could shoot, she hate the ejecting brass. In my old age .45 acp is not fun as it used to be.

WC145
April 14, 2011, 09:39 AM
Your wife may not enjoy shooting a snubby, most of the centerfire calibers give a fair amount of muzzle blast and recoil. Some folks with 9mm snubbies feel the recoil is pretty sharp and that's with steel and aluminum guns, my gun is lighter than those. I don't think it's bad but my wife won't shoot it, I had a steel framed 9mm and that was too much for her as well. It may be better in a K-frame, a little more weight, a little larger grip, I suppose it depends on what you want to use the gun for.

iyn
April 15, 2011, 04:17 AM
How does the 9mm "snap" differ from the 38 +p recoil?
10 year ago I shot 38+p out of a 2" Model 15, I remember that felt like recoil. My friend's sig 220 felt like a snap compared to 1911s glock 21's.

Sport45
April 15, 2011, 06:00 AM
After the conversion can you still shoot .38/.357 or does would the brass split near the base?

WC145
April 15, 2011, 09:48 AM
How does the 9mm "snap" differ from the 38 +p recoil?
10 year ago I shot 38+p out of a 2" Model 15, I remember that felt like recoil. My friend's sig 220 felt like a snap compared to 1911s glock 21's.
I can't speak for the "snap", that's what I've seen from ther folks that have 9mm snubbies. Personally, I think my guns feels the same as it did with .38spl, a bit harsher with 9mm +P+ but nothing like my friend's Model 340 .357mag. I think it's very manageable, even in a gun as light as mine. When I qualified with it I shot 100rds of 115gr FMJ in about 35 minutes with no ill efects, no worse than shooting the same amount of .38spl through a 642 in the same time frame.

After the conversion can you still shoot .38/.357 or does would the brass split near the base?
No, you shouldn't shoot .38spls (or .357mags if that was what he gun was originally chambered for) after the conversion. Standard pressure .38's will bulge the cases and +P's will split them, plus they fireform to the chambers and can be hard to extract.
Of course, you can always have another .38 or .357 cyl fitted to your gun so you could swap them out whenever you like. That would make for a very versatile combo.

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