S&W N Frame bug ....

[Harter66]

I know just enough about them to look really smart if someone knows nothing and really stupid to a knowledgeable person . I will provide what I have and we'll go from there .

The arm in question is an April 1918 built 1917 , so it's just a tick over 105 yr old . It's stamped not English made and has had the barrel cropped to 3.5" .
It's had a 45 ACP reamer poked in it to make 45 S&W headspace on the mouth with .453 throats and a .451 groove .
All 6 holes aligned correctly with the bore as far as good light in 3 axis' will show to the human eye .
End shake / play is tight giving.004 on both ends with moon clips and AR cases with a trade of about .001 to about.003+ at .004 HS .

Enter the issue it appears that the crane is square . It runs 3 chambers like greased glass , 2 are tight in rotation but not overly difficult to fully engage the lock bolt . Of course one rotates out of the tightness and is readily drawn out DA or SA it takes probably 25# vs the 8ish of the other 3 chambers the last chamber requires manual turning . In the 3 chambers that cause the greif the cylinder won't lock closed and hold enough on the 2 hard chambers to prevent cocking.

My belief is that the cylinder is making either a canted or elliptical rotation but I can't see it or really even measure it. It's like a high primer or sizing induced proud case but since it does it empty that's not it .

Because it's not consistent or gapped I don't think it is the crane . It would drag or be difficult all the way around .
As a lone cause the extractor is out as it is flush and square to the cylinder face , without any suggestion of abnormal wear or poor fitting . It's not dirt I've practiced "when in doubt wash it out" cycled immersed in solvent and fully opened .

As I write I wonder if it has a bulge somewhere that isn't worn enough to shine . ........

Where should I look next ? This isn't a new thing , at it's purchase it was cheap enough to assume it was dirt or end play it's been 6 years and I haven't figured it out and don't have an exhaustive S&W book .

[Der Gebirgsjager]

As said many times, difficult to diagnose without actually having it on one's workbench. I think I'd try a new cylinder pin/ejector rod/center pin (whatever name you desire!). Going by your description of the problem, what could it be? It's very unlikely that the cylinder itself is machined unevenly, the yoke/crane seem to be o.k., but the problem is in rotation and the pin is what it rotates on. Finding a new part may be problematic, but a diligent search of the parts suppliers may turn one up. I own two Uberti SSA-type revolvers in .32-20 WCF. Both appear identical, and yet I discovered once when I mixed up the cylinder pins that one functioned properly but the other was locked up. It took me awhile to catch on that I had swapped them, and eventually, by rolling them slowly back and forth over a glass surface I was able to see that one of them wasn't quite straight. However, it worked very well when installed back into the original revolver. I have a 1917 S&W very similar to what you've described, barrel cut back to just over 3", and it works. So, that's my best guess without examining it. Mine isn't reamed out, uses .45 ACP or Auto Rim. You've lost me a bit saying, ".45 S&W".

DG

[TD1886]

How does the cylinder rotate when you have it swung out for emptying and loading? When you turn it does the ejector rod turn true? Do the bolt notches all appear to be the same depth? Do you see and wear marks there on the tight chambers? Report back.

[Der Gebirgsjager]

There is another possibility that comes to mind...less likely, but worth examining. The round, cylindrical portion of the yoke could be slightly bent. Something that is about like fingernails on a blackboard to revolver-educated folks is those who snap the cylinders closed one-handed like the 1930s movie characters. As the cylinder is massive compared to the yoke, when the snap closure occurs the cylinder's inertia wants it to keep moving. The result is usually visible when the revolver is viewed from the muzzle end as a gap (varying widths of gap depending on how much, how often) between the frame and yoke. This is repairable by a couple of methods, the most common being, with the cylinder open, to insert a nylon wedge (Brownell's) through the frame's window between the top of the frame and the cylinder and to tap it into the opening until the desired results are obtained (no formula, just "cut and try" but caution is the watchword). The problem, just speculation, that if this was/is the problem and it was already partially corrected by someone (enough to move it along to the next owner!) then you may not see a gap as described. The possibility exists that, again "if" this was done by someone else that it was over or under done and you have no way to determine which unless you cautiously and carefully continued the process. So, if the cylinder pin swap doesn't work for you I think the best solution would be to take it to an S&W savvy revolversmith. Usually such misused revolvers are a bit out of time, and even if they will fire the indent in the primer may appear well off center.


DG

[rintinglen]

I concur with DG on the problem. I would just about bet that the crane is bent out of true, so that the cylinder rotates off-kilter. This was a very common problem back in the day, when most officers had revolvers and little training. The one-hand, inertial flip, cylinder closure and the hard-slap-whack-it-shut technique both served to warp the tube that the cylinder revolves around. Any (good) revolver smith will have the tools to measure the straightness of the ejector rod and the concentricity of the Crane arbor and would then be able to make the appropriate adjustments. Power Custom has a good video on this repair.

[HWooldridge]

I have to believe that hard rubbing as you described would leave a worn spot somewhere. It's some sort of TIR issue; sounds like chamber 5 is the culprit, with 4 and 6 as the adjacent indicators.

I might remove the locking bolt and the hand, then put the cylinder in battery and rotate it both ways.

[TD1886]

I concur with DG on the problem. I would just about bet that the crane is bent out of true, so that the cylinder rotates off-kilter. This was a very common problem back in the day, when most officers had revolvers and little training. The one-hand, inertial flip, cylinder closure and the hard-slap-whack-it-shut technique both served to warp the tube that the cylinder revolves around. Any (good) revolver smith will have the tools to measure the straightness of the ejector rod and the concentricity of the Crane arbor and would then be able to make the appropriate adjustments. Power Custom has a good video on this repair.

But the OP stated that cylinder mouth alignment to the bore was very good and he measured the cylinder gap every which way to Heaven. If the crane is bent it would show up on the cylinder gap. You have to measure the gap with feeler gauges on both sided to see that they are the same.

[Harter66]

As said many times, difficult to diagnose without actually having it on one's workbench. I think I'd try a new cylinder pin/ejector rod/center pin (whatever name you desire!). Going by your description of the problem, what could it be? It's very unlikely that the cylinder itself is machined unevenly, the yoke/crane seem to be o.k., but the problem is in rotation and the pin is what it rotates on. Finding a new part may be problematic, but a diligent search of the parts suppliers may turn one up. I own two Uberti SSA-type revolvers in .32-20 WCF. Both appear identical, and yet I discovered once when I mixed up the cylinder pins that one functioned properly but the other was locked up. It took me awhile to catch on that I had swapped them, and eventually, by rolling them slowly back and forth over a glass surface I was able to see that one of them wasn't quite straight. However, it worked very well when installed back into the original revolver. I have a 1917 S&W very similar to what you've described, barrel cut back to just over 3", and it works. So, that's my best guess without examining it. Mine isn't reamed out, uses .45 ACP or Auto Rim. You've lost me a bit saying, ".45 S&W".

DG

45 S&W aka Schofield and rimless cut at 1.100 ,

[Harter66]

It didn't occur to me to swap the ejector rod or crane/cylinder assy between Ms April with the issue and Ms August .
Ms August is untouched OM mid August 1918 . Either might figure it out.

[ddixie884]

Those chambers are overly long from the factory and may not be altered. There may not be a ledge, you may just be pushing up against the ball Seat. A loaded 45 ACP will fall well into the chamber and stop with the rear of the cas well into the chamber.

[JMtoolman]

I had one that did the same thing. I found the ejector rod was bent slightly. Only a few thousands. Some cautious bending between wood held in the vice strightened it out. It was somewhat surprising how hard it was to bend. On mine you could see the bend flexing the crane if viewed from the front, the gap in the frame opened and closed as it rotated.

[practical_man]

What you describe sounds a lot like the ejector rod isn’t concentric with the cylinder and yoke. It’s a common problem. It can be causes by rough handling or even the tolerance of the threads.

Checking concentricity is a piece of cake using a dial indicator. 2-3 thousandths variation is acceptable. More than that causes trouble you describe. Ron Power makes a nice tool for the job. It’s sold by Brownells.

It could also be cause by the hand being too narrow, or by the double action sear being damaged. Worst case would be a bent hammer pin (unlikely but not unheard of).

I’d look to the ejector rod first, and the crane while you’re at it. If those are correct then its time to pull the sideplate.

Really tough to diagnose remotely.