On my last range trip (yesterday), I noticed it was hard to cock the hammer sometimes.  Cases had a bright swipe mark across them, about even with the outer edge of the primer pocket.

I figured I needed to clean the gun anyway, so I took out the cylinder and even took it apart.  Nothing seemed particularly filthy, but I started to see a pattern: SOME brands of brass were fine, while others stuck.

My calipers show the R-P cases have a rim thickness of around 0.054 +/-, and the cylinder turns smoothly with R-P cases in it.  PPU and PMC brass has a thickness of around 0.058-0.059, and they drag badly.

SAAMI says .38 Special and .357 Magnum can have rims from 0.049 to 0.060" thick, and the chamber/recoil plate space can be from 0.060 to 0.070".  So it looks like brass that's in-spec isn't fitting, and the headspace on the revolver is under spec.

The drag seems to be more pronounced for cases in one particular chamber, too.

The firing pin hole is not burred; a fingernail slides smoothly across the whole area.

So do I have (over nearly 40 years of ownership) developed decreased headspace?  If it isn't that, what do I do to correct this issue?

Thanks!

Have you been firing .38spl lead bullet loads?  May be a buildup of carbon or lead in the chambers.  It would be different in each chamber.

Also check the front of the cylinder.  With a feeler gage measure the barrel cylinder gap for each chamber.

Have you checked the rear upper portion of the frame window for carbon build up? Also, I had a S&W 25-5 that became difficult to cock and found debris, specifically unburned powder under the ejector star. Cleaned the powder out and normal operation resumed.

Crud under the ejector star is the usual culprit.  It doesn't take much.  Chamber build up from 38 Special is the other normal problem.  Highly unlikely your gun developed inadequate headspace over time.

I have not yet checked the flash gap - it’s on my list.  I completely disassembled the cylinder, including removing and thoroughly cleaning the ejector and the cylinder under it, with the problem persisting, so that’s not it.

The space at the rear of the frame, above the firing pin hole does have some gunk, but I will be able to clean that out pretty easily, and then I’ll re-check the issue.

I have shot mostly .38s through this pistol.  The K frame is reputed to be a “once in a while” .357 Magnum gun, and to be honest my stash of .357 brass is way smaller than my .38 stash.  So it’s quite possible that the chambers have gotten crud buildup in them.

UniqueTek offers a tool called a Slix Scraper; it’s designed to clean cylinders for longer rounds (like .357 or .44 Mag) that have had shorter rounds (.38 or .44 Special) fired in them.  It’s affordable, and since I still plan to fire .38s in all of my .357 revolvers, I think it’s a good investment anyway.

Thanks for the advice, folks.  I spent much of last evening on the Smith-Wesson forum, and got all sorts of good information.  But not practical stuff like “look for crud here” or “gunk builds up in cylinders.”  Thanks a lot for the practical stuff.  Once again, the ARFCOM community has helped me out on an issue that “specialty” sites just ignored or provided minimal information about.

I've done a lot on my revolver, and I'm still having some problems.

I have completely removed any hint of gunk in any of the chambers.  Soaking in Kroil, vigorous brushing, the chamber scraper, all went into getting everything that clean.

The flash gap is between 0.006" and 0.008", without any hint of snagging there.  There is no gunk above or around the barrel's forcing cone.

There is no gunk between the top strap and the recoil plate, either.

It looked like there could have been a bur on the firing pin hole, but I ruled that out.  If there had been one, I'd have felt it by running the edge of a feeler gauge across it.  Nope, no bur.

I completely disassembled the cylinder for the chamber cleaning, so I also got the rim recesses in the cylinder completely clean.  And the extractor's recesses were already pretty clean, but I got at 'em with a stiff brush and got them really clean too.  I DID find a bur on one of the extractor recesses, but it wasn't much (some metal was slightly displaced inward, and a little upward too), and between bronze brushing and a little careful use o 600-grit sand paper, the irregularity is gone.

Now I have less drag, and it is seemingly only affecting one chamber.  It is also apparently dependent on the rim thickness.

Any ideas would be greatly appreciated.

Bent crane or ejector?

Are you running reloads?  Are the primers fully seated?

When you took the cylinder out did you check the end shake measurement?  High speed gases blow past the yoke there could be crude getting built up on the cylinder side of the yoke which might show up as a change in the end shake measurement.

JSG, the ejector seems as straight as I can measure.  And the crane is also apparently true, though that may take someone else’s finer tools/eyeballs to determine.  On the other hand, it looks more like a specific chamber of the cylinder, so I’m cautiously optimistic that the crane isn’t the problem.

Ameshawki, yes, I ran reloads in this revolver.  But I have dragging with empty, UNPRIMED cases, so it’s not a primer issue.

HarryClipper, I will have to do the end shake test to see how the yoke checks out.  While I have cleaned the living snot out of the cylinder and extractor, not so much the yoke...

Thanks for the advice, folks.  I’ll start checking out the yoke as soon as I can.

How did that Slix-Scraper work out?  It didn’t solve your problem, but was it a good tool for cleaning .357 chambers that had seen .38 Specials through it?

It was helpful.  I don't know that it dug out much crud, but it definitely seemed to make it easier to clean the chambers.

I feel that, if nothing else, it broke the glaze on some of the crud.  I used wadding soaked with Kroil first, and some gunk came out.  Then the scraper arrived, and I used it, then used GI bore cleaner.  It seemed like a lot more dirt came out with swabbing the chambers after scraping.

And I think that I'll just keep this tool as part of my usual .357 cleaning routine.  It can't hurt to scrape that last .1" in the chamber.

I haven't had a chance to do the shake test yet - it was a WAY too busy week for me.  I hope to get to it tomorrow...

Bent crane wouldn’t be just one cylinder I think.


Ever remove the cylinder, crane and yoke?   Might be worth going that far and cleaning out the tubes where they fit together.


Edit, nvm I see you did disassemble the cylinder off the frame.

I haven’t cleaned the crane anywhere near as thoroughly as the cylinder and ejector yet.  That comes next, along with testing for shake.