[Standing Wolf]

Why is there a rod in the rebound slide of my pre-agreement Smith & Wesson model 617?

I took my old K-22 to the range Tuesday evening. It did a fine job on slow and timed fire, but the trigger was too stiff for rapid fire in my arthritic hand. I decided to swap the main and rebound slide springs with those in my model 617. There's a slender rod about .75" long in the center of the spring. What does it do? When did Smith & Wesson start using it? What happens if I leave it out?

The model 617 main spring didn't provide reliable ignition in the K-22, so I've ordered springs from Wolff. It's a grand old gun, and the more I use them, the more I like the old Roper stocks, but the original three-pound single action pull is a bit stiff for me.

[Jim Watson]

It acts as a trigger stop to reduce backlash.
I thought it was an old feature and did not know Smith was still using it.

[Jim K]

If you look at the old K-22, you will probably see a little tab sticking out of the frame behind the trigger. That is the backlash stop; it can be adjusted by removing the sideplate.

The pin inside the trigger return spring is the later (and very much cheaper) way of doing the same thing. It often doesn't work too well from the factory, but by putting in an overlength one and carefully working it down, backlash can be eliminated just as with the old type. If the current one allows too much backlash and you want to play with it, a piece of 10 penny nail works just fine and the price is right.

Jim

[Old Fuff]

Jim is correct in saying the purpose of that pin inside the rebound slide is to act as a trigger stop, but they are seldom adjusted close enough too do any good. I think they were used more in "N" frame guns then anywhere else. Post-war "KT" (Target) frames had a built-in stop in the frame. However these were often removed from target-grade combat guns (models 15, 19, etc.).

If the pin is carefully fitted it makes an effective trigger stop, and eliminates any backlash after the trigger releases the hammer. On double-action-only guns it can shorten the trigger's travel and prevent the back of trigger from pinching the trigger finger against the trigger guard.

If it works like it's supposed to I'd leave it in. If it doesn't and you remove it nothing consequental will happen.

Concerning the main spring. Rim-fire cartridges require a heavier hammer blow to reliably fire because the rim is made of thicker material the the cup in a center-fire primer. Keep this in mind when you're playing with springs.

[4v50 Gary]

As suggested, you can take the rod out and there'll be no harm to the gun at all. It can be reinstalled later. However, don't mess with the springs as they provide the energy to drive the hammer forward (& reliable ignition).

[C.R.Sam]

I like to leave the hammer springs alone and replace the rebound springs with factory single action ones. They a bit lighter and full length.

Smith part # 53870000

Sam

[Standing Wolf]

Thank you, thank you, one and all!

I wouldn't have considered the possibility it might be a trigger stop in a hundred years. There's a fair amount of over-travel in the model 617's trigger. Knowing what the little rod is, I'll have to cut down a nail and fiddle around with it. That one's not a tack driver, but an improvement is an improvement is an improvement.

My old K-22 does, indeed, have a stop immediately behind the trigger, and since there's virtually no over-travel, I haven't tried to adjust it.

Thanks again, eh?

[P95Carry]

Damn!!! The info in this place is awesome ..... kudos to THR members.:)

[Mike Irwin]

"However, don't mess with the springs as they provide the energy to drive the hammer forward (& reliable ignition)."

Uh, Gary?

The rebound slide spring doesn't do a thing for hammer fall.


As for the "anti-backlash" rod, I've pitched them from most of my guns. They simply don't work worth a damn, in my opinion, unless you do as Fluff says and spend HOURS fitting it.

No thanks.

[4v50 Gary]

Opps. You're right Mike. The rebound slide serves to return the trigger to its position of rest. Cutting the rebound slide spring reduces the tension on the trigger and slows down the rebound slide's return to a position of rest.

BTW, re: trigger stops, I'd habitually remove them from all service revolvers lest they work lose and jam the trigger.

[Jim K]

Most S&W trigger jobs involve removing 1 1/2 - 2 coils from the rebound spring. This does not appreciably affect return speed but does remove a degree of reliability under adverse conditions. But you can also "roll" that spring, by using a piece of drill rod that fits inside it and holding the spring against the belt sander to trim the outside. This reduces spring tension a bit without making it shorter. (A lighter spring from Wolff does the same thing.)

As to the flat mainspring (hammer spring), I never take stock off the flat, but rather off the edges of the spring. And I never cut the tension screw!

As always when grinding springs, don't let them get hot and always keep water handy for cooling.

4v50Gary, I see the point of removing the trigger stop from a duty/carry gun if you are talking about the old type, but I really don't see how the pin type could work loose. On the old ones, I didn't remove them (leaves a hole that looks odd), just ground them down so they couldn't interfere. They were mostly on target revolvers anyhow; I think the Combat Magnum may have had one, but am too lazy to go look right now.

Another rebound slide trick is to mill lengthwise grooves in middle of the sides and bottom of the slide. Doesn't affect performance or function, but reduces the bearing surface.

Jim

[bountyhunter]

As for the "anti-backlash" rod, I've pitched them from most of my guns. They simply don't work worth a damn, in my opinion, unless you do as Fluff says and spend HOURS fitting it.

Just for grins I cut one and "hand fitted" it to see how good the over travel setup would get. Turns out, it's the same as it was with the stock rod that came in the gun. You need some clearance for the nose of the hammer just under the SA sear to get by the trigger edge so you can't really set the trigger up real tight for over travel. From a cocked hammer, you will probably have the trigger move about .075" past the point where the hammer drops to where the stop rod catches it.

[bountyhunter]

Opps. You're right Mike. The rebound slide serves to return the trigger to its position of rest. Cutting the rebound slide spring reduces the tension on the trigger and slows down the rebound slide's return to a position of rest.

However.... the final action of the rebound slide as the trigger returns forward is to push the hammer from it's forward (ignition) position back to it's rest position. Ergo, the RB slide spring has to push against the hammer's main spring to do that. That means you can use a significantly lighter RB spring (and still get good trigger return) if you use a reduced force hammer main spring.

[Jim K]

I happened to look at my posting above and I said I never cut the tension spring. I meant the tension screw in the front of the grip, which some folks turn out or cut down. I have edited the post. Sorry for the error.

Jim