We finally got some decent weather and I was able to get out today and chronograph a bunch of loads out of my rechambered 360J. For comparison I also used a S&W 637, a Taurus 905 (the Instant Backup model with a short, 9mm length cylinder), a Beretta 8000D Cougar, and a Rock Island Armory .38 Super. All of the results were enlightening, some surprising, and some a bit disappointing. I didn't get anywhere near the velocities out of the 360J that I thought I would but I was able to see the reason why, which I'll get to later. I was shocked by the velocities out of the 905, they were almost equal to the Beretta and easily surpassed the 360J. Also, it was clear to me that what I thought about ammo, based on what I've read, was incorrect. The advantages and disadvantages of barrel length, chamber dimensions, and pressures were obvious.

So, here's the numbers and I'll discuss my thoughts on the results below:

Now, what was clear to me while shooting all of these rounds is that the 9x23 chambering in these conversions is a compromise that doesn't fit anything well, including the 9x23. Since you're starting out with a chamber that is cut for the .38spl (a straight .379"diameter for the entire 1.096" depth) when you recut the chamber for 9x23 (.392" tapering down to .381", but only to a depth of about .870") you end up with gaps at different points in the chamber depending on what caliber you're loading it with. IMO, that is why I got the reduced velocities out of the 360J, I was losing pressure in the chambers and it was evidenced by the soot on the outside of the cartridge cases and some case bulging with some hotter rounds.

So, since I can't think of all of the questions that might be asked, I'll give you a couple of more of my thoughts and then answer or discuss any of your questions or observations:

a. Obviously the 9mm out of a properly chambered snubby is pretty hot compared to the .38spl (Taurus 905 velocities vs S&W 637). IMO, the difference in recoil between the two was negligible, the 9mm is nothing like a .357mag.

b. Given the loss of velocity with the converted cylinder it's a matter of personal opinion if the expense is worth the 150fps difference between the .38spl+P and the hottest 9mm load I had.

c. The current .38 Super loads aren't so super. In fact the velocities I got out of the 1911 weren't much more than you'd expect from the .38acp it was supposed to replace. It does make me want to check out the Corbon loads, though.

d. Barrel length makes a difference with hotter loads, more room for powder to burn = more pressure = more velocity, as evidenced by the Federal 9BPLE numbers out of the Beretta (3.6" barrel) and the HK (4.41" barrel).

e. The cylinder/barrel gap doesn't mean that much. In spite of being a revolver with a short 1.75" barrel, the Taurus 905 velocities were within about 3.5% of the Beretta which has an effective barrel length of approx 2.41" after you subtract the chamber and OAL of the 9mm round.

f. The 9x23 is wicked hot. WW claims 1450fps and it was right on the money out of my .38 Super 1911 (which chambered and fed it without any trouble, I guess that's pretty common). Surprisingly not much difference with felt recoil in the 1911, more noticeable in the 360J but still nowhere near my friend's M&P 340 with fullhouse .357mags. It does sound completely different out of the 1911, more of a crack than a boom, like a rifle. I must say that I am now a fan - a 124gr bullet going 1448fps out of a 1911 is nothing to sneeze at.

g. I'm thoroughly impressed with the velocities from the Taurus, obviously the tolerances are quite close to produce the same velocity from the Federal 9BPLE that I got from the 9x23 Winchester from the 360. I'd love to try these same 9mm loads in a 940 and compare the results.


In conclusion, if I knew then what I know now would I spend the money to convert my 360J..... hmmmm..... Yes, I think I would still do it. It is lightweight (13oz), has more than acceptable accuracy for it's intended use, and gives me close to 1000fps with my duty load (Federal 9BPLE) with similar recoil to a .38spl +P. Also, I can get .357mag velocities with the 9x23 Winchester with less recoil.

Where do I go from here? Good question, I'd like to try a blank cylinder cut to 9x23 from the start and see what kind of numbers I get but that would probably be cost prohibitive. So, I'll pobably stick with what I've got and be happy. My 360 is still what it was yesterday - light, accurate, reliable, versatile, and easy to handle - with more power than a .38spl, just not as much as I had hoped.

Now, let me know what you guys think!

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Did you use the same cylinder for all test in the S&W? Or did you use a different one for the 38s? In my conversion if I use 38s in it, it will split the case.

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So the 130gn FMJ 38 Special is less effective out of a snubby than the old 38 S&W LRN.

...as to .38 Super ammo. You probably chose the two worst examples to test if you are looking to see what Super will do. And you are correct, the Supers loaded by Winchester, Federal and Remington are not much hotter than .38 ACP.

If you want to see what Super will really do get some CorBon. Velocities will run:
115s.... 1450
124s.... 1350
PowR'Ball....1500+

I have chronographed all these loads from both 5" and 4.25" barrels and what they print on the flap of the box is what you get out of the barrel.

Bob

Yes, I only have the rechambered cylinder for the 360, that's why I used the 637 to compare .38spl velocities. Two of the +P cases did split, which didn't surprise me, that's why I didn't try the HydraShoks in it.

I was a bit surprised by how slow they were, that's like wadcutter territory. Can you believe that's what we carried in our Model 15's when I was in the Air Force?! Scary thought!

The Aguila and the Silvertips were all I had available. I'd heard they weren't good examples of what the Super can do but you gotta run what you brung. I am interested in trying some of the Corbon stuff to see what it'll do but I'll have to order it, nobody carries it around here.

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I have 9mm 940 cylinders bored to 9x23.
If you are ever in PA, You are welcome to use one,
Great write up!
Thanks!
Peter

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Just a few weeks ago I shot my Models 60 and 940 over the chrono. With 124 gr. cast bullets and Power Pistol I got 1230 FPS out of the 2" barrel of my 940. I also managed 1160 FPS with 124 gr. Gold Dots. Extraction was very easy. At least one brand of +P+ factory loaded ammo was able to get close to this but extraction was difficult.

As for the .38 Special, it seems that heavy charges of SR4756 with 158 gr. cast bullets really is the way to go and velocity figures of 1100 FPS are in fact attainable.

Dave Sinko

What are the dimensions of a 940 cylinder? I checked with S&W when I first bought the 360 and was told that a 940 cyl could not be fitted to the 360 frame but I doubt it's been tried, certainly not by S&W! I would think that the chambers of a 9mm cyl reamed to 9x23 would work better than starting with the straight walled and head spaced chambers of a .38 cyl. Because the 9x23 is slightly larger/longer than a 9x19 but with the same taper I would think that would be the next best thing to starting with a blank.

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Don't kiss smiling dogs!

The 940 & 940-1 are the smaller frame size that was built on the 38 spl platform..
The 940-2s cylinder is magnum lenth & that would be what would be needed to convert your 360..
I have never seen a 940-2 but do know they exist..
If you got lucky you might be able to get S&W to sell you one if they have them??
Also I tried Corbon +P 38 Supers threw my reamed 940 & the round was "HOT".. Not as hot as a 357 Magnum but reaching in that direction, No cronograph here..
I am tempted to try some 9x23 if & only if it can be had a a decent price.. Good Luck on That Right??
Great write up on the convertion with crongraph results to back it all up..
Guess you'll have to try other brands of ammo..
I also have some 9BPLE & it's deadly accurate from most any handgun I've tried it through, Includeing Beretta92FS, S&W 3913NL, 940 & 547.
I need to get to the range with a 642 that I fitted a 940-1s cylinder too last weekend, It should be fierce @ 15ozs..
Wanted a 942 ever since I heard that S&W made "ONE"..
I have a couple thousand Isreali Sub_Gun 9mms that I'm tempted to try in some of these snubbies..
The 547 shoots them fine but does tend to stick as the preasures are increased & the brass fire forms to the cylinder & I want to be carefull with the 547s extractor segments so I poked them out with a small dowel at the range..
Gary/Hk

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Today I ordered a 940 cylinder from Brownell's. They had two in stock (if anybody is looking for one) and the description is:

I ordered it with my 637 in mind, but it has the same size frame and cyl as the 360. I'm hoping that "New Style" means it is magnum length. I guess I'll find out in a few days.

I'll bet those Corbon .38 Supers pack a punch, I know the 9x23s sure did, though still not as bad as a .357. I like the 9BPLE also, I've got a bunch, about 1000rds. I'm amazed that the 9BPLE was the same velocity out of the Taurus as the 9x23 out of the 360. I got lucky at a nearby shop and found three boxes of 9x23 124JSP that had been sitting on the shelf for a while, I got them for $23.98 each!

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"I was a bit surprised by how slow they were, that's like wadcutter territory. Can you believe that's what we carried in our Model 15's when I was in the Air Force?! Scary thought!"

Not to worry..that was not the same grade of ammo....at least back in the 1980s when a friend of mine was a Captain in the Air Force Security Police. He brought some of that military boxed 130 ball ammo home and it was HOT. Never did chronograph it but from the recoil I am betting close to 1000 fps.

I had one of the 940s and being a .38 Super/9x23 shooter I seriously thought about having the chamber reamed for 9x23. Dane Burns of Burns Custom used to do the conversion but stopped after some "problems". The last time I spoke with him he said he would rechamber the gun for .38 Super with the promise I wouldn't use 9x23s in it if they fit, which starting with a 9mm chamber cut they probably would. I sold the gun to my neighbor instead who carries a 9mm Commander and he loves the gun.

I do have two of the 4" 686 PC .38 Supers but have never chronoed them for velocity loss...a "some day" project.

Bob

WC,
I just traded off a new 940-1 cylinder to Headknocker (aka Gary Sutter). He installed it in a 642, so the new one you get for Brownells may not be "magnum" length. Thanks for the great information on this thread, although I plan on sticking with Speer 124 grain GDHP out of both my 3913 and converted 637.

Pretty please let me know if it works!!

I'd love to do that conversion

Well, I got the new 940 cylinder from Brownell's yesterday. No dice, it is too short to fit either my 637 or my 360. So, unless anyone here needs one and would like to buy it for what I paid, I'm sending it back to Brownell's and I'm going to start hunting for a 940-2 cylinder. I'll start by calling S&W and seeing if they have one they'll sell.

Do any of you know where I might find one if S&W doesn't pan out?

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Don't kiss smiling dogs!

The cylinder listed on Brownells site is for the J-frame not the JMagnum-frame. Brownells is pretty good on their engineering revision numbers for parts.

I just ordered one of the cylinders today. However, I already have a spare 940 barrel on hand as well. I might fit these to an older model 60 that I have. Open the cylinder up for 38 Super and I will be good to go.

940-2 cylinders are going to be hard to find for a while. When they hit ten years past the date of discontinuance, Brownells or Numrich will probably acquire the ones that S&W is holding back for warranty repair purposes.

Yeah The 940-1 Cylinder fit into my 642 No Dash with only the end shake & ratchet needing fitting.
I did have to trim down the center pin & ejector rod as they were magnum J Frame lenth..
Now I can convert from 38spl to 9mm by loostening the end shake screw & swapping cylinders out..
The difference between the 940 & 940-1 cylinders is the early style had the two index pins in the ratchet face & the -1 has the newer style with four angeled & one flat tips to the the ejector/ratchet face assembly..
Thanks to safearm for that cylinder assembly, It worked out great..
Here's a pic of the 642/942 right after convertion, Note: 38cylinder in the background & a Pic of it with my 940 after I put the Spegels back on after tinkering with it..
I will be picking up some 9x23 if I can find some at a decent price to try in my reamed 940..
My standard carry load for either of these is still the 124gr Federal Nyclads in 9mm Para..
Gary/Hk
940 & 942

Attached Images

942.jpg (79.6 KB, 156 views)

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