45 Colt Cylinders on Blackhawks OM vs, NM

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Zeke38

Bearcat
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Mar 22, 2022
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I have a NM Blackhawk that needs a 45 Colt cylinder, Can I use an OM cylinder to fit it. I've found a 44 Magnum cylinder that I want to bore out to 45, however, I don't know if it is a OM or NM cylinder. Will this work. The seller is unable to tell what edition the 44 mag cylinder is. Thanks for your help! Anyone has a 45 Colt cylinder for sale? Bought the gun with the ACP cylinder, guy had lost the Colt cylinder and at the time it was the ACP I was looking for.
 

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princeout

Blackhawk
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Jun 12, 2009
Messages
944
I have a NM Blackhawk that needs a 45 Colt cylinder, Can I use an OM cylinder to fit it. I've found a 44 Magnum cylinder that I want to bore out to 45, however, I don't know if it is a OM or NM cylinder. Will this work. The seller is unable to tell what edition the 44 mag cylinder is. Thanks for your help! Anyone has a 45 Colt cylinder for sale? Bought the gun with the ACP cylinder, guy had lost the Colt cylinder and at the time it was the ACP I was looking for.
I believe the OM 44 and 45 cylinder are recessed head chambered while the NM cylinders are not recessed. Fitment would depend on lengths of the cylinder and the cylinder window.
I also think some of the first NM revolvers came out with OM recessed head cylinders.
Someone who knows for certain will chime in soon.
Tim
 
Joined
Dec 11, 2002
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7,773
Often times the difference is the gas ring in the front of the cylinders, New Models have a barrel "set back" deeper so the ring is LONGER on the new Models........as well as noted above the chamber recess............

CxG6tPEm.jpg
 

Zeke38

Bearcat
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Mar 22, 2022
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Thanks you guys, the 44 Cylinder I was looking at I can now say was an OM. You just saved me so money. I contacted Ruger CS when I first purchased the pistol I called Ruger CS and they advised they weren't doing "cosmetic gunsmithing" at the moment. Ruger CS did verify that the 45 left the factory as a convertible, so that's good.
 

hittman

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Ruger CS did verify that the 45 left the factory as a convertible, so that's good.
Indeed, that is excellent news. I’d pay Ruger the $10 for a factory letter; especially if your gun has the 4 5/8” barrel. Someone here said they made fewer of those than they did the 44 flattops!

Congratulation, this one will surely increase in value for you.
 

contender

Ruger Guru
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"Indeed, that is excellent news. I’d pay Ruger the $10 for a factory letter; especially if your gun has the 4 5/8” barrel. Someone here said they made fewer of those than they did the 44 flattops!


Uhh,, re-read the OP,,,, he has a NM gun, not an OM. He did find an OM cylinder.

As for a letter,, it helps for the Old Models moreso than the new models.
 

Zeke38

Bearcat
Joined
Mar 22, 2022
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Sorry didn't mean to create a stir! With ACP cylinder she shoots!
RtcQe0Kl.jpg
 

contender

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You didn't create a stir,, at all. Quite the contrary,, you got your answers,, !

hittman only did something I've been guilty of as well,,, mis-reading a post. We are all good!

He IS correct in the fact that in the OM 45's,, there were fewer of those built than the OM .44 Ft handguns. Those OM 45's do enjoy a premium,, and especially those that are convertible or that were shipped with a grass g/f. THOSE need a letter to confirm their "as shipped" condition.

On your NM,, yes,, it sure does look like it likes the ACP cylinder. You do need to find a NM Colt cylinder to match.
You now know what to look for,, (the length of the cylinder boss,) but one thing not mentioned was to take your ACP cylinder,, measure the OAL. Buy a Colt cylinder the same length or a few thousands longer. You can then hone down the boss to fit yours if necessary.
Luckily,, the way those were built,, the timing of the cylinder isn't often (almost never) an issue.
Go on a hunt for a NM 45 Colt cylinder. Expect to pay $125-$150 for one.
 

moparclan

Bearcat
Joined
Dec 9, 2013
Messages
35
Bought a recently made stainless .44mag Super Blackhawk with the non fluted cylinder, prefer the fluted ones. Found a fluted .44 mag cylinder couldn't use it because some where along the way Ruger changed the ratchet size/spacing on the back of the cylinder. Be sure to check the ratchet on the cylinder to verify they are the same. It fit and functioned fine on my older new model Supers just not the newer one??
This Bisley .45 Colt cylinder was a perfect drop in fit for my .45 convertible Blackhawk.
26500b
 

DocTone

Bearcat
Joined
Mar 25, 2022
Messages
4
The cyls are not heat treated. And heat treating would just spoil the blue finish.
Barrels and cylinders are not machined from castings, but are produced from bar stock or forgings, depending upon the gun model. Barrels and cylinders are generally heat treated to Rc35 Min at Ruger, whereas other makes are typically 20-24. Ruger frames are generally Rc 28-35, whereas a lot of S&W frames used in the Model 10 and similar guns won’t even register on the C scale, but may be around 80-90 on the B scale. Depth of hardness will be machined out of chambers. Ruger cylinders are heat treated


 

Zeke38

Bearcat
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Mar 22, 2022
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Thanks Doc for the links, especially the one on the Carpenter steels.
 

Hondo44

Hawkeye
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Barrels and cylinders are not machined from castings, but are produced from bar stock or forgings, depending upon the gun model. Barrels and cylinders are generally heat treated to Rc35 Min at Ruger, whereas other makes are typically 20-24. Ruger frames are generally Rc 28-35, whereas a lot of S&W frames used in the Model 10 and similar guns won’t even register on the C scale, but may be around 80-90 on the B scale. Depth of hardness will be machined out of chambers. Ruger cylinders are heat treated


I should have been more specific. Cyls are not heat treated after reaming for a different cartridge. Cyls are not annealed for rechambering, the reaming does not affect the factory heat treatment, and therefore re-heat treating would only degrade the original factory heat treatment quality. Heat treatment doesn't have a depth of hardness, it's the same all the way through; it's not to be confused with case hardening. Rechambering reamers are sufficiently hardened and durable to be able to ream heat treated cyls.
 

Zeke38

Bearcat
Joined
Mar 22, 2022
Messages
34
Thanks for the clarification! Still looking for a Blued 45 Blackhawk NM cylinder or a Stainless!
 

hittman

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If you have a minimum of 20 posts (or messages they’re now called) or are a Contributor you can put a WTB ad in the Classified Section.
 
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Just FYI . . . RENE shows the following last serial numbers for the two guns . . .

OM .44 Flattop = 29860 (pre-prefix numbering, 1956-1962)

OM .45 Blackhawk = 45-23031 (prefix numbering, 1971-1973)

Love the OM .45's! ;)
 
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Onty

Single-Sixer
Joined
Dec 17, 2000
Messages
390
I have a NM Blackhawk that needs a 45 Colt cylinder, Can I use an OM cylinder to fit it. I've found a 44 Magnum cylinder that I want to bore out to 45, however, I don't know if it is a OM or NM cylinder. Will this work. The seller is unable to tell what edition the 44 mag cylinder is. Thanks for your help! Anyone has a 45 Colt cylinder for sale? Bought the gun with the ACP cylinder, guy had lost the Colt cylinder and at the time it was the ACP I was looking for.

The only way is to get cylinder, see would it fit, or fit it, try to cycle revolver and check bore alignment.

Some 25 years ago we were at fellow shooter's house, just after returning from the range. Our host mentioned that he purchased 3 screw Blackhaw in 30 Carbine. My friend pulled out his Ruger Flattop in 44 Magnum, and suggested to try to swap cylinders, to see would they fit. To our amazement, 30 Carbine cylinder had perfect fit in 44 Magnum Flattop, and 44 Magnum cylinder had also perfect fit in 30Carbine revolver. Both revolvers cycled normally, no hard turning or sloppiness in the frame, even cylinder to barrel gaps looked fine. Conclusion was never to have those two revolvers same time on same facility.

Thanks Doc for links for excellent articles! I knew about steels for SRH 454, but first one was real eye opener, even for me, BSME, quite familiar with metal machining and cutting tools.
 

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