S&W 627 9mm Cylinder Conversion

[JMax]

Got bored and remembered that I had a S&W 627 takeoff cylinder from an old friend's revolver. I checked timing on my ICORE match 627, reamed the chambers, assembled with a blued ejector rod assembly and off to the range. It does not like .356 cast bullets, jacketed are OK but it likes Bear Creek Supply .358 coated 158 gr RN bullets, now is time for load development. I shot those bullets for years in ICORE matches with great results. Now I have a dual caliber 627.[smilie=w:

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[JMax]

I have now fired about a thousand rounds thru this cylinder in 9mm, 38 Super and 38LC. Results are listed with a photo of 25 hard groups fired DA off a soft rest using my 72 year old eyes.
1) 9mm, .356" bullets have poor accuracy at 25 yds and exhibit yaw while jacketed loads are on par with 38 Super and 38 Long Colt loads at 25 yards
2) 38 Super groups are excellent with the revolver slightly leaning to the 850 ft/sec load using 158 gr .358" RN cast bullets
3) The base line is my ICORE LC load of 3.2 gr Clays and a 157 gr .358" RN cast

Some fellow reloaders expressed concern shooting 38 LC or 38 Special loads the 9mm/38 Super chambers. All of my LC brass had 3-5 reloads so the experiment began. Mean Time to failure or MTF was 13 additional 38 LC reloads while those shot in a Smith 28 exhibited a 20% failure rate at 21 reloads. Doable but not desired.

No 9mm or 38 Super failures observed date.

Now I have a reliable 9mm/38 Super cylinder for my Smith 627 in addition the the 357 Mag cylinder.

A fun and engaging project.

[mattw]

That would be fun! But my 627 is the 6 shot and I doubt that cylinders exist for it.

[rockrat]

How difficult was it to ream the cylinder for 9mm. I have a 6" Model 28 that I could convert

[DougGuy]

Seems like a lot of unsupported freebore until the boolit reaches the ball seat and then enters the throats.

[mattw]

Doug, would on be for fun... Besides a cylinder for a 627 is not going to appear and I will not touch nor let anyone touch the original. Keep in mind, the 627 no dash had the shortest cylinder ever in any S&W 357 if memory serves me today.

[JMax]

The 627 8 shot cylinder is setup for moon clips or individual rounds so if the cylinder is not mooned already then that needs to be done first.

There is a longer free bore in the converted cylinder but did not adversely effect accuracy at 25 yards with my eyes and shooting DA. Perhaps at 50 and beyond. There was a bigger impact using .356” cast bullets while .356 jacketed 9mm shot about as well as .358” cast at 25 yards.