trigger staging

[Ignatz]

I picked up an older 6" slab sided 686 PC 7 shot gun that was basically brand new. I did the standard Jerry Miculek "trigger job", and everything feels great. The problem is that when I close the cylinder the trigger job gets tight at the last 10% of the trigger pull. Five of the 7 cylinders, I could live with, but 2 of them get tight at the last part of the pull.

This is an older generation gun with the firing pin in the hammer.

Also when I cycle the gun, the cylinder locks in with a distinct "clunk". Just lightly running my finger lightly over the ratchets, I can feel sharp edges, like it was never finished.

Any sugestions, comments please.

[PatJones]

Check the runout on your ejector rod before you make any changes. It will make things feel tight.

[Ignatz]

That spins nice and straight, thanks.

[pskys2]

You may have a couple of ratchets that aren't fit quite right, or it may have a burr there. The older style are a bit touchier on the hand/ratchet fit.

[bountyhunter]

I picked up an older 6" slab sided 686 PC 7 shot gun that was basically brand new. I did the standard Jerry Miculek "trigger job", and everything feels great. The problem is that when I close the cylinder the trigger job gets tight at the last 10% of the trigger pull.

Sounds like a fit issue with the ratchets. They have to be fitted individually in a process called balancing so they all carry up the same. SW used to do this on new guns back when they had gunsmiths. These days, I would assume any new SW gun has fit problems depending on how many bananas the min wage monkeys had on the day they built the gun. Not sure when yours was built.

A gunsmith should be able to fix this easily so that all the cylinder positions feel about the same and none are binding. It sounds like the tightness occurs after the cylinder locks and the hand has to slide by the ratchet. Some gunsmiths just stone the hand edge to make it narrower but it's much better (but takes more time) if the ratchets are fitted so they are all the same and the hand width is perfect so it has zero clearance but doesn't bind.

Edited May 19, 2014 by bountyhunter

[practical_man]

That spins nice and straight, thanks.

Did you put it on a dial indicator? If not, you might. I had a model 67 that did what you describe. The ejector rod looked fine to the eye. When I put it on a dial indicator it was over .050 off true. After I straightened the ejector rod all was well.

[Ignatz]

Thanks, it really runs true in the gun when I cycle it. I'm going to put a couple hundred rounds (or more) thru it to help loosen things up. I also have 2 hands on the way to "probably ruin".

While trying to track down and pinpoint the problem, I took apart my 581 and tried to put parts in this 686-4, but nothing comes close to fitting in this gun.

The other "odd" issue with this gun is that 2 different hammers I put in this gun get stuck when I assemble the gun and fire it. I have to tap the hammer back "lightly" with a punch and hammer to get it unstuck.

Its like the firing pin hole in this gun is fitted for the firing pin that came with the gun. And I get one and sometimes two light hits with a I'm guessing a 7.5# trigger.

I can feel the hammer nose first touch the lower part of the frame, then gently glide into the firing pin hole. My 581 and other K frames with the older hammer nose, just go directly in the firing pin hole without any extra friction.

Thanks, Rob

[bountyhunter]

Thanks, it really runs true in the gun when I cycle it. I'm going to put a couple hundred rounds (or more) thru it to help loosen things up. I also have 2 hands on the way to "probably ruin".

While trying to track down and pinpoint the problem, I took apart my 581 and tried to put parts in this 686-4, but nothing comes close to fitting in this gun.

The other "odd" issue with this gun is that 2 different hammers I put in this gun get stuck when I assemble the gun and fire it. I have to tap the hammer back "lightly" with a punch and hammer to get it unstuck.

Its like the firing pin hole in this gun is fitted for the firing pin that came with the gun. And I get one and sometimes two light hits with a I'm guessing a 7.5# trigger.

I can feel the hammer nose first touch the lower part of the frame, then gently glide into the firing pin hole. My 581 and other K frames with the older hammer nose, just go directly in the firing pin hole without any extra friction.

Thanks, Rob

Well...... hammers and triggers are fitted pieces. At least, on the older guns they certainly were fitted. maybe the new MIM parts hold tolerance so tight they no longer fit them (?)

Edited May 22, 2014 by bountyhunter

[Tom E]

Well...... hammers and triggers are fitted pieces. At least, on the older guns they certainly were fitted.

"fitted"? How? Please explain what was done to "fit" the hammers and triggers.

[bountyhunter]

Well...... hammers and triggers are fitted pieces. At least, on the older guns they certainly were fitted.

"fitted"? How? Please explain what was done to "fit" the hammers and triggers.

I believe the Kuhnhausen manual goes into detail about fitting. At minimum, there is a delicate fit process on the DA sear that sometimes requires removal of metal from the hammer in the area below the SA cocking notch to get a proper "handoff" when the hammer motion transitions from being lifted by the trigger beak to the DA sear. Other fits are the SA sear notch itself.

I remember having a long conversation with one of the gunsmiths at SW about fitting hammers and sears back in the mid 90's. Bottom line, the rule of thumb is that if you drop in hammers and sears without fitting it's a maybe go maybe not proposition. If the hammer/trigger are dropped in as a set from an identical model, you have your best chance. If parts are swapped at random, look out. The physical position of the boss pins in the frame that thins mount on have tolerances between guns.

It's similar to the "drop in" kits for 1911 guns that have sears and hammers: some work OK, many don't because the spacing is critical but the tolerances sometimes are not tight enough.

Here is one random story about a guy who "dropped in" a new hammer:

http://smith-wessonforum.com/s-w-smithing/236761-effect-fitting-da-hammer-sear-timing.html

"Did a bit of planned smithing on two of my revolvers this morning. Item one was to replace the Target width hammer on my 610-3 with a 0.400 service width hammer. Item two was to replace both the hammer and trigger in my 625 JM with blued MIM parts in 0.400 widths.

Because of this I had purchased 2 seperate 0.400 inch service width hammer assemblies which included the DA sear. These parts come with a sharp tip on the sear where it engages the DA sear step on the trigger and this tip must be fitted to the trigger in order for the trigger to reset consistently. Basically, if you leave the Sear on the hammer sharp you'll find that the trigger won't reset on every return.

After spending some time studying how the lockwork functions in double action I realized that if this sear tip is chamfered too much it will allow the hammer to release a touch earlier in the trigger stroke. So, in fitting the hammer sear to the trigger I was careful to only chamfer the tip to the point where the trigger was resetting properly and not go any further. The end result is that the chamfer is about 0.010 narrower than the chamfer on the factory supplied hammer sear.

Testing has revealed that my 625 JM now drops the cylinder stop just a bit earlier in relation to the hammer fall than it did as set up by the factory. What is actually happening is that the sear is releasing the hammer a hair later in it's stroke however the effect is the stop drops a bit earlier. It's not a lot and likely not enough to matter one bit, however it does point that there are "tuning points" in the lockwork that can effect the timing. Quite simply, if you're fitting a new hammer sear to the trigger you can cause "late" timing if you go too far."

Edited May 23, 2014 by bountyhunter