Cylinder replacement - easy?


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Arp32
December 14, 2012, 12:18 AM
I've been lucky enough to inherit a Combat Masterpiece K-frame from a buddy, only problem is it needs a new cylinder. Three of the chambers must have opened up a bit because I can load six but only eject 3. Those last three I have to force out.

I'm a bit ignorant on this, is a cylinder replacement a drop-in affair or should I send it to a gunsmith?

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Jim Watson
December 14, 2012, 12:23 AM
Gunsmith or factory job.
The timing must be set as well as the cylinder gap.

Arp32
December 14, 2012, 12:24 AM
Thanks, will do. A man's got to know his limitations.

BCRider
December 14, 2012, 02:45 AM
Before you panic it may be simply due to a built up crud ring of fouling that has burnt onto the chamber walls.

Get yourself a .40 (not .357) caliber bore brush and chuck it into a hand drill and work out the chambers along with some cleaning solvent. It doesn't need to spin crazy fast but it'll reduce the work load by using the electric drill. Work at it for a while and then go try the gun again. I'd bet you an E-Beer that all the chambers will be fine after a good brush n' solvent workout.

If this doesn't do the trick I can only imagine that someone fed it a few double charges at some point and bulged the cylinder. But I'd expect to see some signs of such bulging on the outer surface as well.

Hey, at most it'll cost you a bore brush and a bit of time.

evan price
December 14, 2012, 09:45 AM
Changing the cylinder is a mechanically very simple job. If after cleaning it you still have a problem and want to change it, find a good used cylinder and put it in. You MAY get lucky and your timing will be OK. Its certainly. Not a guarantee. But its not much time to try and won't mess up anything as long as you don't start filing or forcing parts. And if you need a cylinder anyway what's it hurt to try. The last one I changed was a drop in with a very nice used cylinder and star I got off of gunbroker. Timing and lockup and endshake we're absolutely perfect. Your experience may vary however.

aHFo3
December 14, 2012, 10:07 AM
Power tools and firearms always make me a bit nervous. You probably will already do this, but just in case: be sure to remove the cylinder from the frame and yoke. The yoke retension screw is located on the Right side of the revolver in the most forward position, near the address. Good luck!

Arp32
December 14, 2012, 10:49 AM
Thanks RC, I'll give that a shot. Got nothing to lose as I expected to replace it anyway.

Say that doesn't work out and I do replace the cylinder myself, how will I know the timing is off? Is it just that the cylinder will not have completed its rotation to the next chamber by the time the hammer falls? I'd be willing to try it if it was the kind of thing where I couldn't make it any worse than it already is.

MrBorland
December 14, 2012, 10:59 AM
Three of the chambers must have opened up a bit because I can load six but only eject 3. Those last three I have to force out.

So, the problem is the 3 tight chambers? The loose ones aren't too loose? If the problem is only 3 tight chambers that aren't fixed with a good cleaning, a gunsmith can ream them to spec. Have him check the throats, too, to be sure they're in spec.

Arp32
December 14, 2012, 11:06 AM
They aren't tight at all when I load it to begin with. All 6 load easy, just like my model 64.

But after firing, I literally have to force the brass out with a screwdriver. It takes a good amount of force.

I am imagining the chamber is slightly bulged and when I fire the gun, the brass is expanding into the void and thus getting stuck. That's my theory, at least.

Usually I shoot 6, unload and reload the three, spin the chamber and pull the trigger 6 more times to see if I flinch. Nice training aid, but really I'd like to have it fully functional.

rcmodel
December 14, 2012, 12:52 PM
Clean it with the drill & .40 bore brush like BCRider suggested first.

Then with the chambers sparkly clean, hold the cylinder up to the light and carefully look at the reflections inside each chamber.

If they are bulged, they will most likely be bulged or dimpled at the locking bolt notches as that is the thinnest part of the chamber.
And you should be able to easily see it.

There should also be indications of what is sticking on the fired brass.
Look for shiney spots on the brass that match the locking bolt notch locations.

rc

MrBorland
December 14, 2012, 01:16 PM
I've also seen an instance where the cylinder was reamed, but the job was botched, such that the chambers weren't perfectly cylindrical. Stuck brass that's out of round might point to that, and it's easy enough to check if you have calipers.

Arp32
December 14, 2012, 09:19 PM
Clean it with the drill & .40 bore brush like BCRider suggested first.


Haha, I was reading quickly on my phone and totally thought that was your post, RC. My apologies, BC!

Arp32
December 14, 2012, 09:23 PM
Thanks guys. Headed to the range Sunday so I'll have a chance to see if a good cleaning does anything. Just need to grab a .40 brush as that's not a caliber I shoot.

BCRider
December 15, 2012, 12:22 AM
MrBorland raises a great point.

These days a set of imported digital calipers is cheap to buy and has a wide variety of applications to most any reasonably avid firearms owner. If you don't already have a set it would be a worthy addition to your tool set. With it you can then measure the cases at various spots and increments around the diameter to check for bulged brass from the tight chambers vs the easy to eject empties. The brass is springy enough that it won't reform totally to the final end diameter upon being ejected even if some fairly heavy force is needed.

The ejected brass from the tight chambers can also be tested in the chambers which are OK to see if they were stretched enough to be a tight fit trying to be re-inserted. That alone can suggest the nature of the problem as being fouling or if the brass is actually being bulged due to some damage.

Oh, and it is also not a bad idea to wrap some masking tape around the cylinder so that you can number and reference the chambers during all this testing. Otherwise you don't know which came from where.

highpower
December 15, 2012, 01:29 AM
I have done this job a couple of times. I replaced the cylinder on both a K38 and a Model 29. Both times it worked perfectly, but it may have been because I reused the ejector star from the original cylinder so the timing stayed the same.

rcmodel
December 15, 2012, 01:41 AM
So far, nobody has convinced me there is anything wrong with a Model 15 Combat Masterpiece cylinder, except it maybe needs a good through cleaning and inspection to see what he can see.

To think S&W reamed it wrong back then in the first place borders on foolishness.

Unlike today, a S&W K-38 Combat Masterpiece with three bad chambers wouldn't make it past the night shift janitor.
Let alone the quality inspections, and proof firing guys.

rc

highpower
December 15, 2012, 09:14 AM
To think S&W reamed it wrong back then in the first place borders on foolishness.

Unlike today, a S&W K-38 Combat Masterpiece with three bad chambers wouldn't make it past the night shift janitor.
Let alone the quality inspections, and proof firing guys.

+1

S&W had pretty good QC back then, I just can't imagine them letting one out the door with that problem.

Now, what kinds of abuse it may have been subjected to since then is anybody's guess. The M29 I refereed to in my earlier post was an early model that I bought cheap due to finish issues. When I went to shoot it I found that all the chambers were bulged. It was not something you could see, but after firing, the empties were extremely hard to extract.

I have the tools to measure chambers and I found that all of them were bulged by an average of .0065. I was able to find another cylinder with recessed chambers and after I fitted the original ejector star the timing was spot on.

There is no doubt in my mind that someone shot overloaded .357's through it and ruined the cylinder.

To the OP:

I see cylinders on Gunbroker and Ebay on a fairly regular basis and if you shop wisely, you should be able to find one for a reasonable price. Even if you are hesitant to install it yourself, once you have the part it should be easy to find a gunsmith to install it.

MrBorland
December 15, 2012, 09:34 AM
To think S&W reamed it wrong back then in the first place borders on foolishness.

To clarify - the botched reaming I referred to was part of a "tuning", done long after the gun left the factory.

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