NM cylinder in OM frame

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ruddy

Bearcat
Joined
Jan 8, 2016
Messages
4
Does anyone know if a new model 30 carbine cylinder will fit in an old model frame?
 

contender

Ruger Guru
Joined
Sep 18, 2002
Messages
25,150
Location
Lake Lure NC USA
As noted, the frame size is the same.
However, pay close attention to the cylinder boss & how far the barrel protrudes into the frame. On the NM's, some folks have been using 32-20 ammo, because of the rim & ease of reloading & extraction. The gap at the rear of the cylinder of the NM's allows this,, while the OM guns do not have the same spacing.
Quite often, the main differences in NM's & OM's is this spacing, caused by the cylinder boss. So, a NM cylinder may have a boss that's too short for an OM gun.
 

Hondo44

Hawkeye
Joined
Apr 3, 2009
Messages
8,041
Location
People's Republik of California
As posted above by flattop 44, yes it will with the usual caution to find one as close to the dimensions of your existing cyl. They don't all just "drop in" and may need some slight fitting, especially the over-all length.

Is your purpose to be able to shoot 32-20 Winchester cartridges in it? The new model cyls (non-recessed flush case heads) will do it.

Even though the .30 Carbine is a rimless round it's a good thing the NM lets the .30 case head stick out more than just the rim thickness since the .32-20 rim is .016" thicker. But may bind slightly in some revolvers and the rear cyl face just needs a slight facing off.

.32-20 cannot be fired in OM Ruger .30 Carbine cyls as is. The chambers seat the .30 carbine rimless case heads flush with the cyl face, and the rimmed 32-20 case head won't fit far enough into the end of the .30 chambers. By simply recessing the chamber mouths to the .061" thickness of the .32-20 rim they will shoot in the OM chambers. Or Facing off the rear of the cylinder .061", will fix that. Either method will still allow you to shoot 30 carbine because no matter what you do to the rear face of the cyl it won't affect proper and safe chambering of the 30 carbine ammo since it headspaces on the case mouth.

Don't be surprised if you find an early New Model gun with a left over Old Model cyl. You can call it a transition model so common in any type manufacturing as changes evolve.

The Old Model cyl has a firing pin groove cut in like Ruger .22 cyls, etc. Obviously by shortening the New Model cyl, the extra step and cost of cutting the firing pin groove was eliminated but still affords the same firing pin protection.
ClK44kPl.jpg


Try this for other alternative cartridges in the new model cyls:

You'll probably find the .32 H&R Mag and the .327 Federal Mag much more fun to shoot without the ear splitting report of the 30 carbine round. Performance of the .327 Fed Mag is closer to the 30 Carbine and with fine accuracy although you may get some split cases occasionally.
 

ruddy

Bearcat
Joined
Jan 8, 2016
Messages
4
Thanks for the responses. Yes, I would like to shoot .32-20 cartridges in my OM Blackhawk w/o modifying the original cylinder, because I don't have the capability to do so.
 

Hondo44

Hawkeye
Joined
Apr 3, 2009
Messages
8,041
Location
People's Republik of California
You can rent a 32-20 reamer on-line, just Google. It'll recess your chamber the thickness of the 32-20 rims. And you can still shoot 30 carbine as safe as shooting 30 carbine in the new model cyl.

A new model cyl will need overall length fitting at the front gas ring to your frame's cyl window unless you found one the exact same length and that's highly unlikely. But recessing the chambers in your old model cyl is so much easier; you can do it by hand, because there's so little metal to remove. And less expensive than buying the new model cyl.
 
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