I have since a few years a Ruger BH, blued version, convertible model with both the .357 and 9mm cylinders from 1976 (33-3xxxx serial number). I had the opportunity to buy a second one, stainless steel this week for a real bargain price. It is also from 1976 (33-1xxxx serial), which I will unfortunately only get in a few months due to the paperwork involved. Both are 'New Models'.

Is there any chance that the convertible 9mm cylinder fits (as a drop-in) to the second gun ? What should I watch for if it 'seems' to fit ?

Thanks and all the best from Belgium - B686

Sometimes they will just drop-in & fit.

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John 3:16
WAR EAGLE!

i have a "New Model" BH 357 from the 70's (not sold as a convertible), i bought a stainless 9mm BH cylinder on ebay a few years back, it fit and timed fine (used gauge rod down bbl thru all chambers), the problem i have is the OAL of some 9mm cases wont allow them to be loaded. I think the chamber depth on 2 or 3 chambers needs to be reamed a few thousandths deeper (i'm hesitant about the easy fix -shortening the cylinder by a few thou.) to allow normal function with all sammi spec OAL brass. I dont know if the convertible models had any different tolerances cylinder/frame.
I'll also be interested in other comments. You got me rambling...

A stainless dual-cylinder Blackhawk from 1976? I'd buy it in a heartbeat. Even if the cylinders don't switch, that is a great find.

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Heavily armed old man.

I bought a 9 mm cylinder to put in a non convertible Blackhawk. I needed to shorten it to fit and balance both front and rear clearances. I didn't want to file on the barrel nor remove it to shorten it. I ended up with a good shooter and 0.004" cylinder gap.

Just based on my one experience they may be fitted to the gun. In either case they are fun shooters.

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Front sight and squeeze

I bought a 9mm/.357 Ruger Blackhawk on the 21st birthday in 1977. I ran some 9mm through it, but accuracy was terrible and the .357 cylinder remained in it until I traded it off some years later.

While is seems, on the surface, to be a good idea, the execution leaves something to be desired.

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Only a cold warrior

Just in case my first post in not 100% clear : the blued RBH is a convertible, while the stainless one I just bought is .357 only. Here in Europe we unfortunately have only blued convertibles . That's why I wanted to 'fix' this, as the blued one has an alloy frame I do not like so much and it's quite scratched and has a few dings (except for the both cylinders). Stainless is so much easier to keep clean. Besides that, the 9mm and .38/.357 precision out of the blued one is on pair - I am very satisfied about that. I reload both calibers. Further they both have 4 5/8 barrels, which I find esthetically very nice .

Thanks a lot for the positive feedback, as I wouldn't have been tempted to buy a cylinder only (fearing it would not fit at all). Having both guns, I know the 9mm will at least fit the blued version and worst case scenario the blued one would end up as the 9mm only. Sorry about the bad picture - that's all I have.

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If you consider I got it for about 300 $ - don't tell or I will be kicked out of here

This is the blued one :

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I have this Ruger New Model Blackhawk 10mm/.40 convertible. I put aftermarket stocks on it as the factory stocks fit horribly...


Also this Colt New Frontier .44-40/.44 Special convertible...

Thanks for your post, i will take some new measurements (BCG) with 9mm cylinder and see if i have the room to get a nice fit like you. (its been years since i shelved that project). Did you only need to remove from the front of cyl.? did you need to machine "lathe turn" the back of the cyl. as well? (i know we are only talking .005 to .008")
Thanks, Mike

No, I only removed materiel from the front.

As a suggestion, establish a base line with the stainless 357 before you start any modifications. You want to make sure that it shoots well enough to follow through.

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Front sight and squeeze

Love the convertible idea! Have a New Model Blackhawk in 45ACP/45Colt. works great for me! No moon clips for ACP a +. Bob

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Thanks, i'll get some measurements/refresh my memory and let you know what i think. I bought the blue New model back in the late 70's early 80's, then i saw a 9mm stainless cyl. on ebay (30 years later) and bought it on a "lets see if this will work" kind of approach. It fit! all chambers align w/bbl using gauge rod. started loading 9mm and found some were too long and i could not rotate the chamber as the case head interfered with the breach face lip on the frame. I thought it may have been the chamber depths. But after reading your posts it re-lit my interest. Both cylinders OAL measure 1.978 +/-.003".
After reading your post i checked the BCG's .357=.005.
9mm=.012 +.001/-.000.
So if i machined .008 off the small protruding front cyl. bushing.... math would say i would reduce my BCG to~.004" and increase the space behind the cyl. (between the rear face of cyl. to the frame breach face) by .008" which may be enough for the cases to index properly past the "breach face lip".
My concern, perhaps unfounded due to the linear forces when firing, and the (space filled with the case heads) is the "new" .008" gap at the rear between the index star and the frame.
Is there any end shake concerns? I think i was hesitant to shorten the cyl. length without fully knowing what i was doing.
Thanks for restarting my interest!

This approach would create an extreme excess endshake condition. At that point, the B/C gap measurement would be totally meaningless as it would be a variable from .004” to .012”, as the cylinder flopped around .008” back and forth.
If you were to try this this, a possible semi-fix would be to install an endshake shim between the cylinder rachet and the recoil shield. But, you may then have headspace issues.
This topic has been discussed often on the various Ruger related forums, as endshake conditions can be quite problematic in the Blackhawk, compared to something like the Colt SAA.
The consensus is that such a problem is best remedied by returning the gun to Ruger to have a new cylinder fitted.

Separately, this thread topic is kind of curious. While the .45 ACP/Long Colt convertibles have a certain practicality, retrospectively the 357/9mm convertible has been looked upon mostly with puzzlement or even scorn.
Writing in the 1970s, noted gun scribe Bob Milek reviewed both the .45 and .357 converibles and deemed the latter to be mostly useless. At that time, 9mm was not a particularly admired cartridge. It was also not cheap! And, besides the ballistic inferiority of the 9mm, at least in this application, the accuracy was consistently mediocre.
However, the .357/9mm convertible did have one saving grace, at least to some end users. The 9mm cylinder could be readily converted to other cartridges!! Perhaps the most popular and successful being the wildcat (figuratively and literally!) .357 Bain & Davis. This “blast from the past” was a bottleneck cartridge based on a necked down .44 Magnum case.
Yes, it’s a “handloaders only” proposition, but it really packs a punch!

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Respectfully, not wishing to offend anyone, but I do not fully get what you mean.

If we consider what is 'useful' not much is left over when speaking about single action revolvers. They have very little interest as defensive tool when compared to a 21st century polymer pistol. Over here civilians owning handguns have them purely for range fun and for me a part of the fun/interest is in the versatility of the convertible BH. Also, in Europe, we have about ten times more choices and lower prices on 9mm cartridges compared to all other calibers (unfortunately). Besides 9mm we have little choice and have to take whatever the shop has, even for .22 LR.

I hear and respect what Bob Milek thought about this 50 years ago, but that doesn't change anything concerning my interest in this subject.

I am however extremely grateful to all the great responses I got. They inspire me to pursue further (taking as much caution as possible) when I will have the stainless BH.

No 45 AR either!

Ivan

While I remember reading Bob Mileks opinion, I also read where Skeeter Skelton mentioned in a column that his 357 Blackhawk had rarely seen the 357 cylinder as his son Bart had shot nearly 10,000 rds of 9mm through it. I didn't imagine him doing that if it wasn't accurate.
At the time, no one shot the 9 mm in competition as the theory was the higher pressure cartridge could not compete with the 45 acp. Today it is a different story. My three Blackhawks have never seen anything but cast and they have not been driven hard. [357/9mm, 44 special and 45 Colt/ACP].
I find plenty of accuracy and fun shooting 9 mm in a Blackhawk.
https://www.castpics.net/subsite2/By...0Blackhawk.pdf
Here is some of John Goins thoughts, past president of Cast Bullet Association.

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Front sight and squeeze