J
Jose
Because Buffalo Bore claims it achieves that performance within the SAAMI pressure envelope of 38 Special +P. Which is a good deal lower than .357 Magnum.
How they do it, I have no idea.
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Changing cylinder in S&W J frame from 38spl to 9 mm
- Thread starter Number 6
- Start date
Because Buffalo Bore claims it achieves that performance within the SAAMI pressure envelope of 38 Special +P. Which is a good deal lower than .357 Magnum.
How they do it, I have no idea.
Maybe I can help...
I can speak with some authority one the subject of converting .38spl J-frames to 9mm because I studied the possible ways of doing it and ended up having one converted. I could have purchased a used 940 but I wanted a lightweight 9mm snubby and the 940 weighs about 22oz. I purchased a new scandium framed 360J (13.3oz) for my project and had it turned into the gun I wanted but couldn't buy. I've been shooting and carrying that gun for two years now and am very pleased with how it turned out.
First, on the cylinder swap, it can only be done using an older pre-J-magnum framed gun because that's what the 940 cylinder will fit. The newer frames (which all current J-frames are built on) use a longer cylinder and the 940 cylinder is too short to work.
Second, rechambering an existing .38spl cylinder is not a big deal. My gun was rechambered by Mark Hartshorne at Pinnacle High Performance. The conversion consists of boring the chambers to 9x23 dimensions, cutting the cylinder face for moonclips, and chamfering the charge holes. Because the chambers are cut to 9x23 a converted gun will not only shoot 9mm Luger (9x19), it'll also shoot 9x21, 9mm Largo, 356TSW, 38 Super, 9x23 Winchester, etc. Yes, a couple of those are higher pressure loads, but remember, not only did S&W make the 9mm 940, they also made 300 PC 940's chambered for 356TSW which generated pressures in the same range as the 9x23. These guns and their cylinders were stainless steel, no special metallurgy, and handled the pressure just fine. My gun has the same scandium frame as the M&P 360 .357mag and (per S&W) all of the .38spl/.357mag cyls are made from the same blanks, the strength of the new scandium and steel framed guns shouldn't be an issue. If I was converting an aluminum framed gun (642, 637, etc) I'd take it easy on the hotter loads in the interest of prolonging the life of the gun.
It's important to note that you don't want to shoot .38's through converted gun, the cases will fire form to the chambers and stick and +P loads will split the cases.
Third, the argument against these conversions because of poor accuracy shooting .355 bullets through .357 barrels is bunk. That one to two thousands of an inch just don't make that much difference. I've seen no loss of accuracy shooting 9mm from my gun compared to shooting .38's before the conversion. I've qualified with my gun and scored within 2 points of my score with my full size duty gun shooting the MCJA LE Pistol Qualification Course.
Finally, if you want a 9mm snub nosed revolver your choices are very limited - 940's, SP101's, Speed Sixes (if you can find them), and Taurus 905's. I carry a 9mm on duty and wanted a lightweight 9mm snubby for BUG/off duty use. The problem was that all the choices I listed above are steel and heavy, that's why I had my gun built. In addition to the caliber conversion I had Pinnacle do an action job, chamfer the forcing cone, smooth, round, and polish the trigger, half bob the hammer, and install a fiber optic front sight. I had Robar coat the cylinder with NP3 to make it rust proof and I added a set of Crimson Trace LG-105 laser grips.
Was it expensive? Yes - close to $1100 all together, including the purchase price of the gun, though it could be done for less.
Was it worth it? Yes - I have exactly the gun I wanted. It is light, accurate, reliable, very fast to reload, and it uses my duty ammo, which is hotter than the equivelant .38spl without the muzzle blast and recoil of a .357mag.
I hope this info helps and if I anyone has any questions I'll be happy to try to answer them.
Here's a couple of pics -
Perfect score - 50/50 using 115gr FMJ -
I can speak with some authority one the subject of converting .38spl J-frames to 9mm because I studied the possible ways of doing it and ended up having one converted. I could have purchased a used 940 but I wanted a lightweight 9mm snubby and the 940 weighs about 22oz. I purchased a new scandium framed 360J (13.3oz) for my project and had it turned into the gun I wanted but couldn't buy. I've been shooting and carrying that gun for two years now and am very pleased with how it turned out.
First, on the cylinder swap, it can only be done using an older pre-J-magnum framed gun because that's what the 940 cylinder will fit. The newer frames (which all current J-frames are built on) use a longer cylinder and the 940 cylinder is too short to work.
Second, rechambering an existing .38spl cylinder is not a big deal. My gun was rechambered by Mark Hartshorne at Pinnacle High Performance. The conversion consists of boring the chambers to 9x23 dimensions, cutting the cylinder face for moonclips, and chamfering the charge holes. Because the chambers are cut to 9x23 a converted gun will not only shoot 9mm Luger (9x19), it'll also shoot 9x21, 9mm Largo, 356TSW, 38 Super, 9x23 Winchester, etc. Yes, a couple of those are higher pressure loads, but remember, not only did S&W make the 9mm 940, they also made 300 PC 940's chambered for 356TSW which generated pressures in the same range as the 9x23. These guns and their cylinders were stainless steel, no special metallurgy, and handled the pressure just fine. My gun has the same scandium frame as the M&P 360 .357mag and (per S&W) all of the .38spl/.357mag cyls are made from the same blanks, the strength of the new scandium and steel framed guns shouldn't be an issue. If I was converting an aluminum framed gun (642, 637, etc) I'd take it easy on the hotter loads in the interest of prolonging the life of the gun.
It's important to note that you don't want to shoot .38's through converted gun, the cases will fire form to the chambers and stick and +P loads will split the cases.
Third, the argument against these conversions because of poor accuracy shooting .355 bullets through .357 barrels is bunk. That one to two thousands of an inch just don't make that much difference. I've seen no loss of accuracy shooting 9mm from my gun compared to shooting .38's before the conversion. I've qualified with my gun and scored within 2 points of my score with my full size duty gun shooting the MCJA LE Pistol Qualification Course.
Finally, if you want a 9mm snub nosed revolver your choices are very limited - 940's, SP101's, Speed Sixes (if you can find them), and Taurus 905's. I carry a 9mm on duty and wanted a lightweight 9mm snubby for BUG/off duty use. The problem was that all the choices I listed above are steel and heavy, that's why I had my gun built. In addition to the caliber conversion I had Pinnacle do an action job, chamfer the forcing cone, smooth, round, and polish the trigger, half bob the hammer, and install a fiber optic front sight. I had Robar coat the cylinder with NP3 to make it rust proof and I added a set of Crimson Trace LG-105 laser grips.
Was it expensive? Yes - close to $1100 all together, including the purchase price of the gun, though it could be done for less.
Was it worth it? Yes - I have exactly the gun I wanted. It is light, accurate, reliable, very fast to reload, and it uses my duty ammo, which is hotter than the equivelant .38spl without the muzzle blast and recoil of a .357mag.
I hope this info helps and if I anyone has any questions I'll be happy to try to answer them.
Here's a couple of pics -
Perfect score - 50/50 using 115gr FMJ -
I can speak with some authority one the subject of converting .38spl J-frames to 9mm because I studied the possible ways of doing it and ended up having one converted. I could have purchased a used 940 but I wanted a lightweight 9mm snubby and the 940 weighs about 22oz. I purchased a new scandium framed 360J (13.3oz) for my project and had it turned into the gun I wanted but couldn't buy. I've been shooting and carrying that gun for two years now and am very pleased with how it turned out.
First, on the cylinder swap, it can only be done using an older pre-J-magnum framed gun because that's what the 940 cylinder will fit. The newer frames (which all current J-frames are built on) use a longer cylinder and the 940 cylinder is too short to work.
Second, rechambering an existing .38spl cylinder is not a big deal. My gun was rechambered by Mark Hartshorne at Pinnacle High Performance. The conversion consists of boring the chambers to 9x23 dimensions, cutting the cylinder face for moonclips, and chamfering the charge holes. Because the chambers are cut to 9x23 a converted gun will not only shoot 9mm Luger (9x19), it'll also shoot 9x21, 9mm Largo, 356TSW, 38 Super, 9x23 Winchester, etc. Yes, a couple of those are higher pressure loads, but remember, not only did S&W make the 9mm 940, they also made 300 PC 940's chambered for 356TSW which generated pressures in the same range as the 9x23. These guns and their cylinders were stainless steel, no special metallurgy, and handled the pressure just fine. My gun has the same scandium frame as the M&P 360 .357mag and (per S&W) all of the .38spl/.357mag cyls are made from the same blanks, the strength of the new scandium and steel framed guns shouldn't be an issue. If I was converting an aluminum framed gun (642, 637, etc) I'd take it easy on the hotter loads in the interest of prolonging the life of the gun.
It's important to note that you don't want to shoot .38's through converted gun, the cases will fire form to the chambers and stick and +P loads will split the cases.
Third, the argument against these conversions because of poor accuracy shooting .355 bullets through .357 barrels is bunk. That one to two thousands of an inch just don't make that much difference. I've seen no loss of accuracy shooting 9mm from my gun compared to shooting .38's before the conversion. I've qualified with my gun and scored within 2 points of my score with my full size duty gun shooting the MCJA LE Pistol Qualification Course.
Finally, if you want a 9mm snub nosed revolver your choices are very limited - 940's, SP101's, Speed Sixes (if you can find them), and Taurus 905's. I carry a 9mm on duty and wanted a lightweight 9mm snubby for BUG/off duty use. The problem was that all the choices I listed above are steel and heavy, that's why I had my gun built. In addition to the caliber conversion I had Pinnacle do an action job, chamfer the forcing cone, smooth, round, and polish the trigger, half bob the hammer, and install a fiber optic front sight. I had Robar coat the cylinder with NP3 to make it rust proof and I added a set of Crimson Trace LG-105 laser grips.
Was it expensive? Yes - close to $1100 all together, including the purchase price of the gun, though it could be done for less.
Was it worth it? Yes - I have exactly the gun I wanted. It is light, accurate, reliable, very fast to reload, and it uses my duty ammo, which is hotter than the equivelant .38spl without the muzzle blast and recoil of a .357mag.
I hope this info helps and if I anyone has any questions I'll be happy to try to answer them.
Here's a couple of pics -
Perfect score - 50/50 using 115gr FMJ -
That's wicked nice. You can't beat that with a stick !
Number 6
NES Member
Wow, Thanks for the very detailed response WC145!
For a follow up question, how can you tell the Pre-magnum J frames? Is there an indicator? Are the non dash models pre-magnum? I was reading on the smith and wesson boards that only the .357 J frames are the magnum frames.
Thanks again!
For a follow up question, how can you tell the Pre-magnum J frames? Is there an indicator? Are the non dash models pre-magnum? I was reading on the smith and wesson boards that only the .357 J frames are the magnum frames.
Thanks again!
Your welcome!
You can tell the difference by the size of the frame window and the length of the cylinder, I think the change over came around 1996. I'm not sure on dashes, S&W has so many guns that start and stop production at different times. I have an older M36 and I'll take a picture with of it with the 360J and post it so you can see the size difference. Of course, another issue you'll run into with the cylinder swap is the scarcity of the cylinders, I don't think there are any more around. S&W doesn't have them, Numrich Arms used to but it looks like they're out now, too.
If you really want a 940 they can be had in the $650 range if you look around. I could have saved money buying an original but I didn't want a 9mm snubby for back up that weighed almost a pound and a half empty, that was the impetus for the project - nobody made what I wanted.
Holy Crap. The word "envy" just falls so far short of what I'm feeling. And you rub salt into the wound with such high quality photos of the finished product.
Needless to say I printed and saved this thread. I've got a older S&W 042 just aching for some work. I need to give Pinnacle a call.
Needless to say I printed and saved this thread. I've got a older S&W 042 just aching for some work. I need to give Pinnacle a call.
Sorry! I appreciate the compliments but, honestly, it's just a working gun.
Here's a pic of a 317 with an older 36, it illustrates the difference in the size of the cylinder window between the original J-frame and the J-magnum frame. According to the SCSW the J-magnum frames were introduced in '96 and all of the J-frame models were switched by Oct '97. The J-magnum cylinder window is 1.73 inches, so that should help to narrow things down if you're looking for a "donor" piece.
640-940 Cylinder Conversion
Hi There,
I'm a new guy here, but I've been at this gun thing for a while. I did the conversion a while back and posted it on PAFOA so here it is:
S&W 940
Coolest thing I've ever done to a firearm, and it came in at less than $150.00! The only visible giveaway that something is different is the frame lug, which is thicker on the 940 than it is on the 640. Endshake is more with the cylinder open as a result, but it doesn't hurt anything.
Oh and by the way, the guy at S&W also told me that a typical factory 940 barrel slugged out at .357 rather than .355 and that the .002 difference didn't matter. I can confirm this with the ridiculously tight groups my .38 barrel shoots with the 9mm round.
Anyone else think Ruger should step up and make the LCR in 9mm?
Hi There,
I'm a new guy here, but I've been at this gun thing for a while. I did the conversion a while back and posted it on PAFOA so here it is:
S&W 940
Coolest thing I've ever done to a firearm, and it came in at less than $150.00! The only visible giveaway that something is different is the frame lug, which is thicker on the 940 than it is on the 640. Endshake is more with the cylinder open as a result, but it doesn't hurt anything.
Oh and by the way, the guy at S&W also told me that a typical factory 940 barrel slugged out at .357 rather than .355 and that the .002 difference didn't matter. I can confirm this with the ridiculously tight groups my .38 barrel shoots with the 9mm round.
Anyone else think Ruger should step up and make the LCR in 9mm?
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I'm a bit late to this thread, but I've converted two 637-2 Airweights to 9mm using titanium .38Sp/.357Mag cylinders reamed for 9mmx19 & Moonclips. I'm in the process of doing a third now. Accuracy is decent (better than me), and I like the 12 oz weight. I use 147gr ammo to minimise the potential for cylinder face erosion on the titanium cylinders.
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richc
NES Member
I have a Smith & Wesson 547 that shoots 9mm without moon clips. There's a fascinating history behind that handgun written by NES's own Jim Finnerty:
Vintage Pistols - Smith & Wesson 547 Range Report
I also have a Ruger revolver that has both a .38/.357 and 9mm cylinder.
For me they are both novelties. I bought the 547 for a great price and it's unfired. I do getting a kick out of shooting the Ruger, though.
Vintage Pistols - Smith & Wesson 547 Range Report
I also have a Ruger revolver that has both a .38/.357 and 9mm cylinder.
For me they are both novelties. I bought the 547 for a great price and it's unfired. I do getting a kick out of shooting the Ruger, though.
That's an interesting extractor.
Each of my three 637s has the original stainless .38Sp+P cylinder and yoke, a titanium .38Sp/.357Mag cylinder and yoke, and the 9mm cylinder and yoke. Sorta feels like I've got J-frame cylinder assemblies running out my ears.
9mm recoil out of the 12oz revolvers is brisk, but not excessive. I alternate carry between them and my Micro 9.
Each of my three 637s has the original stainless .38Sp+P cylinder and yoke, a titanium .38Sp/.357Mag cylinder and yoke, and the 9mm cylinder and yoke. Sorta feels like I've got J-frame cylinder assemblies running out my ears.
9mm recoil out of the 12oz revolvers is brisk, but not excessive. I alternate carry between them and my Micro 9.
dcmdon
NES Member
Or just buy an LCR in 9mm. And save
1) the cost of putting a 9mm cylinder in a J frame.
2) the cost of $300 worth of trigger work. The LCR has the best double action trigger in the business. Its comparable to a J frame with significant trigger work.
It really is tough to beat the LCR as a replacement for the J frame except on one criteria, aesthetics.
1) the cost of putting a 9mm cylinder in a J frame.
2) the cost of $300 worth of trigger work. The LCR has the best double action trigger in the business. Its comparable to a J frame with significant trigger work.
It really is tough to beat the LCR as a replacement for the J frame except on one criteria, aesthetics.
