S&W Model 64 Issue

jimmyj · #1 11-23-2016, 04:51 PM

Hi:
My Model 64 (no dash) has an issue:
When firing slow double action, on one of the chambers the action will lock up just prior to the hammer falling.
Opinions ??

Thanks,
Jimmy

armorer951 · #2 11-23-2016, 05:07 PM

Need more information.....Does it function normally DA and SA when dry fired after the cylinder has been removed and the cylinder release is held back?
If so, more than likely the problem is associated with the cylinder assembly/hand. Long ratchet perhaps, damage to one of the ratchets, dirt or debris under or on the extractor, damage to the hand or hand window, damage to a cylinder stop slot, and the list goes on.

jimmyj · #3 11-23-2016, 08:27 PM

Hi:
Everything works normally empty. When loaded and firing double action the one chamber locks just before the hammer is released by the sear.

armorer951 · #4 11-23-2016, 09:16 PM

So it doesn't pull all the way though on one chamber....or the hammer hangs on one chamber? Is it the same chamber location each time?

jimmyj · #5 11-23-2016, 09:55 PM

yes, the same chamber

armorer951 · #6 11-23-2016, 10:11 PM

Probably damage to that particular chamber's ratchet, perhaps a burr. If you have a magnifier, take a close look at the bearing surface on the ratchet for that chamber. Ratchet for the chamber at 12 o'clock is the one directly below and the the right of that chamber. (looking at the face of the extractor)

jimmyj · #7 11-23-2016, 10:24 PM

Thank you for the information

Hondo44 · #8 11-24-2016, 01:33 AM

The first thing I check in this situation is the barrel/cyl gap. Since you say it dry fires fine, that's the only thing that can change once a gun heats up from firing.

When it occurs, look at the gap to confirm you have a light space thru the gap from top to bottom. Also Is the light space even and the same width on the bad chamber as all the others? Check the front face of the cyl for a rub mark from the end of the barrel.

You might have slight "run out" (not square) on the face of the cyl.

If the cyl is rubbing on the barrel, a few strokes with a file and stoning on the end of the barrel at the point where it rubs the cyl face will correct it.

Let us know what you find.