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Old November 21, 2012, 12:40 PM   #17
RKG
Senior Member
 
Join Date: June 18, 2009
Location: Boston
Posts: 289
Quote:
With a M-29 made ten years ago again shooting double action...sometimes when the trigger is pulled the hammer woudl drop but the transfer bar would be out of position--so it would not fire. I tightened the tension on the mainspring strain screw and that helped...I then spray lubed the internals--made it worse. Did a carb cleaner flush and it now works just fine..any ideas what was going on with that. I have four N farme S & W pistols and this is the only one that "acted up" like that. I do not use heavy loads in it, prefering medium loads.
I wouldn't make a diagnosis without having the revolver in front of me. However, I can observe:

There is no transfer bar in a S&W DA revolver. I presume you are referring to the 1947 hammer block.

Positioning of the hammer block is controlled by a pin on the rebound slide that rides in a cam slot in the hammer block itself. The rebound slide, in turn, is positioned by a strut connecting it to the trigger (for rearward movement) and the rebound slide spring (for forward movement). It is theoretically possible for the rebound slide to be hung up so as to be too far aft (given trigger position) but not for it to be too far forward. (I say "theoretically possible" because I've never seen it happen with any S&W revolver.) When the rebound slide is aft, the hammer block cammed down (so as to enable full hammer travel), while when the rebound slide is forward, the hammer block is cammed up (so as to interdict full hammer travel). So if it really was the hammer block position that was causing your problem, my guess would be that the hammer block may be a bit deformed. But I stress that, long distance and sight unseen, this is just a guess.

People have been loosening the mainspring tension screw for decades. This leads to all sorts of problems, but since the mainspring tension has no effect on position of the hammer block, so I don't think it caused what you have reported.

In any event, this revolver should be examined and, if necessary, repaired by a qualified S&W smith.

Quote:
Had a problem with a M-57...shooting single action, when cocking the hammer the cylinder would sometimes not rotate and lock as it should. I removed the side plate and lightly oiled the critical areas and never had teh problem again
Same caveat about distant diagnoses. I'm not sure what "as it should" means, but generally sluggishness in cylinder rotation is caused by either crud under the extractor star, a bent ejector rod, or a partially unscrewed ejector rod. Please note that some ejector rods are right hand threaded and some are left hand threaded; you have to know which applies to your revolver before trying to adjust the ejector rod seating.
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