9mm conversion cylinder work

[Screwball]

Not to be a dick, but why? What's the gain being able to shoot 9mm in a .38? As Willie pointed out, there are some potential PITA issues with 9mm bullets in a .357 tube.

Before you chop a perfectly good .38, google the rabbit hole of Ruger Blackhawk conversions.

9mm gives you a lot more bullet choices, across a different weight spread, with higher velocity. Also shortens up the length of the reload (9mm in moonclips are shorter than .38 in moonclips). Recoil is subjective, but I noticed no noticeable difference between.38 +P and standard pressure 9mm.

In regards to 9mm in a .38/.357 barrel, there are usually no issues. I kept my .38 cylinder for my 642-1, and don’t notice any noticeable difference in accuracy. I read the Ruger convertible threads, which both pushed me towards a .45 New Vaquero Convertible and made me hesitate with the 9mm conversion. Results of the latter really make the Ruger topics come into question, in my eyes... because I shouldn’t have the results if there wasn’t some type of other factor involved. Don’t know what it is, but can confidently say you won’t have issues with a 9mm conversion... if you don’t abuse the gun.

[jeep45238]

Not to be a dick, but why? What's the gain being able to shoot 9mm in a .38? As Willie pointed out, there are some potential PITA issues with 9mm bullets in a .357 tube.

Before you chop a perfectly good .38, google the rabbit hole of Ruger Blackhawk conversions.

I reload 9mm, conversions for the 1050 aren’t with the cost to me, and it would allow one caliber to stock. Logistical purposes for me, but I’m still debating the red pill or blue pill.


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[JimCunn]

I've got three 12.5oz 637-2 J-frames converted to 9mm titanium cylinders. I did it both for the increased power of the 9mm over the .38Sp and for compatibility with my Micro 9 and my Browning Hi-Power. So far, no crimp issues.

[358156hp]

You're going to have some wicked freebore with this conversion. a 38 spl case is 1.166 in long, and the diameter averages .379 full length. A 9mm case averages .380 at the case mouth, but the case is only .754 long. 9mm factory bullets normally run .355 to .356 in diameter, so that 9mm bullet will travel over 1/4 inch unsupported before it even gets close to the cylinder throats. What sort of accuracy are you guys getting with these converted revolvers? I saw 4 inches at 25 yards mentioned earlier, was that shot from a rest by hand, or is that a Ransom Rest figure? This assumes the throat starts at the end of the 38 spl case length, which it never does. The dimensions show above are case dimensions, since I couldn't find any chamber dimensions handily available. The case dimensions above came from Lymans Pistol & Revolver Handbook if it matters. That freebore can also potentially reduce chamber pressure, leading to reduced velocities.

There is effective 38 spl self-defense ammo available, and the selection for short barreled revolvers is steadily growing. I also had a pair of 649s years ago, and while the recoil wasn't especially heavy, it definitely was sharp to the point of being uncomfortable, I sold them off and bought a 640 and a 649 in 357 mag to replace them.

[Clusterfrack]

I tested crimp jump in my wife’s 9mm LCR using HST 147. I can’t find the exact numbers but I posted them on the LCR thread a while ago. While there were measurable increases in COL, the amount was small enough not to be of concern—as long as you don’t repeatedly reuse a round that has been chambered.

[Screwball]

What sort of accuracy are you guys getting with these converted revolvers?

I did 2” at 15 yards, two handed... semi-rapid fire. The RO that thought he was going to teach me how to shoot got a 6” group... not counting the round that was off paper.



A 1/4” isn’t as bad as shooting .45 Colt out of a cylinder chambered for 3” .410 shells.

[JimCunn]

"What sort of accuracy are you guys getting with these converted revolvers?"

There's no perceptible deterioration in accuracy. Coke can at 25 yards.
In my case, the converted titanium cylinders that I used in the 637-2 were originally .357 Magnum, so freebore should be compared with that, not with the .38Sp. With 147gr ammo, chrono velocity averages 29 fps faster than the same round out of a 3.5" semi-auto.

At 12.5oz empty, recoil is brisk, but not objectionable or unpleasant.

I did one, and was pleased enough that I then did two more.

[JimCunn]

"There is effective 38 spl self-defense ammo available,"

That is true, but I can't use it in my Micro 9 and Browning Hi-Power.

[willie]

When employing moon clips and reloads, you can crimp the bullets with a roll crimp which will eliminate bullet jump. Simply buy and use jacketed bullets made for .38 spl/.357 mag. Their diameter will be .357, and each will have a crimp groove. Since the case is head spacing on the moon clip, there is zero problem using a roll crimp. Establishing tight bullet pull is still required.

As a tinkerer, I understand the desire to experiment and encourage you to do so. In the past and perhaps now, military .45 ACP and 9mm ammo had a cementing or glue type substance applied to the bullet to assist with holding it in place. So did rifle ammo. Color was black. At one time Brownell's sold a product that could be used for this purpose. No doubt the same is used in other industries. From a ballistics standpoint, 9mm ammo is achieving velocity because it is loaded to a very high pressure compared to standard .38 Spl ammunition. The same revolver that will accept 9mm ammo can also be safely used with hot 38 Spl ammo. Producing a hot and safe .38 Spl reload is not difficult.

[talos]

Excuse my ignorance here, I know little about revolvers but have been interested in 9mm for a while. Mostly because I have lots of 9mm ammo for my semis.

Does the moonclip cut in the cylinder preclude using 9mm without moonclips? If so, could you get a conversion cylinder made up for 9mm without moon clips?

I've read moonclips can be problematic due to bending issues. I think Caleb Giddings was someone who discussed that. Maybe I am mis remembering but is there any chance moonclips could bend while in the gun, causing a failure of cylinder to turn? I'd prefer adding even a small amount of reliability, even if it's 1%, and lose the ability to quickly eject/reload. Because if I was down to carrying 9mm in a revolver, I won't be reloading it during a fight.

Also how hard is to change cylinders? Is it just one or two fasteners? Any fitment issues to swap cylinders back and forth multiple times?