An afternoon with a 9mm J frame notes

[ccmdfd]

Has anybody tried having the chambers honed? A common procedure on competition nine-shooters.

There was a 940 around here that had been cut for 9x23 - .38 Super, still usable with clipped 9mm P that the seller said extracted freely.

Wow.

9X23 out of a J frame! That has to be a hoot to shoot.

[Outpost75]

Great write up. Thank you.

I’m unfamiliar with the concept of trailing edge failure. If it’s not too much trouble, would you mind explaining to some of the slower students in the class?


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The common 9mm chamber has a square shoulder at the stop surface where the case mouth rests to provide correct headspacing.

When lead cast bullets are used, the bullet base begins to upset before leaving the case mouth, such that the bullet base is scraped in exiting the case.

Accumulation of these lead deposits causes in hard cylinder rotation because ammunition does not fully contact the chamber stop surface, but is is impeded from seating fully due to the lead fouling.

Breaking the sharp corner of the chamber stop surface to provide a chamfer successfully mitigates against this effect.

[Outpost75]

Has anybody tried having the chambers honed? A common procedure on competition nine-shooters.

There was a 940 around here that had been cut for 9x23 - .38 Super, still usable with clipped 9mm P that the seller said extracted freely.

Honing or polishing the chambers reduces adhesion of fired brass to the chamber walls and makes the set-back and "pistoning" situation worse. This had been done to a second 940 I bought off GunBroker, and I fixed it by roughing the chamber walls slightly with a 180 - grit lap when doing the chamber mod. Works fine now.

Full-pressure 9x23 I would expect to give hard extraction. US .38 Super should be OK. Ruger produced a few .38 Super/9x19mm Service Six revolvers for Columbia and 9x21 for Commercial sale in Italy.

[jandbj]

IIRC, S&W made at least one 940 in 356TSW (aka 9x21.5).

[jandbj]

https://gunsmagazine.com/gear/the-356-tsw/

[JimCunn]

I kind of go in the other direction.
I start with an Airweight 637-2, lighten it up with a titanium .357 Mag cylinder and ream it for 9mm.
I've done two for 9×19 and one for 9x23.

[358156hp]

Has anybody tried having the chambers honed? A common procedure on competition nine-shooters.

There was a 940 around here that had been cut for 9x23 - .38 Super, still usable with clipped 9mm P that the seller said extracted freely.

I've had two 940s so far and am not in the market for another one. My first one I bought from a local cop who had the afore mentioned ammunition issues with it. The trouble was that he was required to use only Department issue ammunition in his backup, and whatever the City issued in those days locked the gun up. S&W sent a call tag for the 940 and supposedly honed the cylinders to make it function with the issue ammo. By the time he got it back he had made up his mind that he didn't trust it and sold it to me, using the funds to buy a Glock 26 IIRC.

I took it to the range and found it to be reliable with the same issue that LPD issued, but it was really unruly to shoot. The recoil wasn't heavy, but it was sharp. I kept it for a short time, then sold it at a gunshow. The only grips that please me were Uncle Mikes 3 finger groove rubber grips from a 640 which made the gun difficult to conceal.

The second one came in one of those complicated trade situations, and was of later production than the first. It behaved poorly in my eyes again, why did I expect it to be different? A coworker fell in love with it and offered me more than it was really worth so I let it go. I ended up with a 640 and a 649, both .357 mag guns that I mainly carried commercially loaded wadcutters in anyway.

[TheNewbie]

I kind of go in the other direction.
I start with an Airweight 637-2, lighten it up with a titanium .357 Mag cylinder and ream it for 9mm.
I've done two for 9×19 and one for 9x23.

How is recoil?

Any bullet jumping the crimp issues?

[JimCunn]

Painful.
Guns weigh 11.5 ounces to 12.5 ounces depending on which grips are installed.
I haven't had any crimp jump issues. Muzzle energy with 147 gr loads averages about 292 ft-lbs at average 952 fps.
These are my favorite guns, and I use one the one in the photo for primary carry.

[titsonritz]

Any bullet jumping the crimp issues?

This something I'd be concerned about with the super light weight 9mm revolvers. I've had .38 spl pull bullets and lock up the action on my 342 and with 9mm have much less of a crimp seems like it would have the same potential.