S&W extractor alignment pins

[Shimitup]

Just curious, anybody know how common it is for extractor alignment pins to fall out. I was at the range with my son shooting my 17-5 yesterday, today while cleaning I saw one of the pins hanging out the back of the extractor noticing then that the other was missing. A bit disconcerting considering the gun only has about 1500 rounds through it. It took about an hour to fix, I had to trim some #53 drill shank down to .0565 and cut to .2 that seemed to give me about a .0006 press fit. I'm quite certain that I know when the first pin came out yesterday, I was double action shooting when on the second or third shot on a particular cylinder full when the trigger seemed to hang very early in the stroke, I released the trigger, dropped the muzzle perplexed, cocked it single action lined up fired it and finished the cylinder double action. Almost certainly when I ejected that load of brass I also tossed the first pin. The new ones aren't going anywhere they're hard and tight. I almost put the gun away for another days work but one of my pet peeves is a broken gun in the safe thus Memorial Day afternoon in the shop.

 

[Jim K]

Not a real common problem, but not unknown and I have replaced some. I used drill rod or spring stock and made them to a press fit just as you did. I am not sure how that happens, but I guess it is those old tolerances again - a hole that is slightly too large and pins that are slightly too small.

Jim

 

[Shimitup]

I noticed that S&W's solution to a press fit is to punch the top of the hole to reduce the diameter, in my book that's not a proper fit since it only reduces a shallow ring right near the surface. I suppose this is one of details to keep an eye on in a self defense gun, as I witnessed it could certainly hang one up. A friend of mine has a J frame I ought to look at and give these pins a tug. This reminds me of a thread from a few weeks ago regarding revolver vs auto reliability. I can't remember for sure but might have been you, Jim that said something about revolvers being utterly reliable until something breaks, Yep, clearing a stove pipe is much faster than messing with loose pins in a cylinder.

 

[rcmodel]

I noticed that S&W's solution to a press fit

S&W's final solution was to stop using them all together.
New S&W's don't have them.

Course, they also changed the ejector rod to a D shape and it does the aligning now.

rc

 

[Shimitup]

RC, you sure about that? That almost seems unworkable, the tolerances on the flat for proper indexing seem like they would have to be so tight it would bind with the slightest bit of grime. Unless they cut the cylinder bores real tight and let the case do the work which for the variations in cases and ease of extraction doesn't seem like a good idea either. Glad I have an old one. (actually not that old, 1988)

 

[Jim K]

Having the extractor go back in place properly is only part of the reason for those pins. They also take the strain if the extractor rod is unscrewed without placing cases in the chambers. S&W solved that problem by angling the arms of the extractor in both directions so the extractor rod can be screwed/unscrewed with no damage to the extractor. I think that change might have been more a matter of speeding production at the factory than preventing problems in the field, but it does the job in either case.

Jim

 

[Shimitup]

I know that's an important function of the pins but was actually thinking in terms of indexing, the hand precisely advancing the cylinder to the next lock up in the notch. I like to check this out by cocking one slowly with a finger lightly dragging the cylinder to simulate as if it were working with a bone dry or nasty cylinder bearing. So often with lightly used or even new ones I've handled they fail to lock in on several cylinders until I let go or nudge it forward. I know with normal shooting it's likely even with poor fitting of the star that inertia will carry the cylinder to lockup before the hammer gets down. I still can't imagine without the precise locating of pins getting good hand/lock timing. Basically I'm just picky about my revolvers, I just like it when the hand comes up on each cylinder and it takes out about 2/3's of the available slack in that cylinder notch. I'm definitely going to check out what S&W has done next trip to the gun store. I can just hear the salesman now, picky picky picky! The plus side is with the new and slightly over sized pins in my gun the timing has nudged forward where my loosest cylinder is just about where I like it, now I get to set the other 5.

 

[Shimitup]

Jim, my apologies for being so dense in the face of your perfectly good explanation. I was handling a new 7 shot 686 today and with my strong reading glasses made out all the opposing angles on the extractor. It jogged my memory realizing that I actually did see one a few months back thinking no further than what an odd looking extractor I was looking at. Innovative idea to get rid of the pins. I'm sure the pins were a holdover from the days of manual machining and hand fitting. When I'm digging around in an older gun I still marvel at the skills of what can be done by a guy standing at a manual machine tool. I still prefer the pins by the way.

 

[Jim K]

Ideally, the extractor will stay in place against the force required to turn the cylinder in normal firing, but none of the systems to do that really are needed when the gun is loaded because the cartridges themselves provide all the alignment that is needed. The pins or a similar system are also used to ensure that the extractor does not get out of alignment during the extraction process, a problem on early revolvers where the extractor could get loose due to wear and fail to keep in alignment. (Colt's old extractor was screwed onto the extractor stem and heavily staked to prevent it from turning; also one extractor arm had a little hump that fitted into a corresponding notch in the cylinder. S&W tried to improve on that with the pins, and I think succeeded.

I think between the revamped extractor stem and the new extractor, S&W has solved all the problems in that area and made the guns less costly to produce at the same time.

Jim