Round stain on side of cylinder

[mitchjt]

I have several N frame stainless steel Smith revolvers that develop a round stain on the side of the cylinder just above the chamber near the discharge end. It appears that it forms from the escaping gases that swirl around the screw hole in the top strap. If so, can this screw hole be plugged?

 

[DonD]

If that happens on all cylinder charge holes I'd say it is just a matter of propellant gasses and clearances. My .500 Mags don't do that but my Ruger SP101 does that all the time and is completely sound mechanically. Don

 

[colt_saa]

The front most screw securing the rear sight is too short or occasionally not screwed in all the way.

When it is not flush with the topstrap a strange reflection of gasses occurs and you get the dot on the cylinder.

This only occurs in revovlers after the cange to the D&T frames. Prior to that, the screw was located forward of the cylinder face.

Call S&W

 

[ridgewalker]

Thanks for explaining the little carbon dot on the front side cylinder. Pretty much all my revolvers have this and I have to admit it never occurred to me that it was from the screw hole in the top frame. That makes sense. I have come to accept the carbon dots as just part of shooting. Do you fellas do something to the hole to eliminate the carbon dot?

 

[Nemo288]

The best (and only real) way to fix that is install the correct length screw.
You may be able to get these in various lengths at Numrich or Brownells.
If you can only get one a little long, cut it off to the exact length needed.
This takes a proper screw cutting tool and maybe a little filing to remove the burr.

===
Nemo

 

[3rdgeargrndrr]

my 460 does that with just one round, but wipes off with some mother's alum/ mag polish. thank god for stainless

 

[blacklabbob]

My new 627 does it on all cylinders.