625PC Hammer weight Adjusting

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Bearbait in NM

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Greetings, and I hope this is in the correct forum. I recently purchased a new 625PC in 45 ACP. It's my first S&W revolver in quite a long time. I have am having trouble getting Kuhnhausen's book right now, but I want to fiddle with the hammer weight, mostly in DA. I have read many hundreds of posts over the last couple of weeks here, in helping to choose the gun, and understand hammer weights v. primers. Not new to triggers or smithing, just new to S&W's.

For the current spec's, the strain screw is tight, and it has the ribbed main spring (Wolff?). Double action is 11 lbs 4 oz. Single action is 4 lb 2 oz. I picked up the Wolff Reduced Power Rebound Sprink Pak, with weights 12-16 lbs all marked reduced.

The first question is would anyone know what the stock rebound spring weight would be? And I assume this spring will not affect primer strike, only the net DA pull weight and the reset speed? The only way I can figure to test would be diaassemble, replace, reassemble and check the pull weight. Knowing the stock spring spec might save me some work and buggered screw heads, testing all 5 weights ;^).

The second question is after setting the rebound, and adjusting the main. My plan was to back the strain out in increments, test against CCI primers, and note the final weight that I want. I would then dress the screw head down to get that weight with it seated tight. Does this sound reasonable?

From what I have researched here, I am thinking that I can knock perhaps 2 pounds off the DA pull, and likely be safe with any primer. And FWIW, I was shocked the factory DA pull is over 11. My experience is with Colts, and it feels a whole lot lighter than 11.

Thanks,

Craig
 
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MG,

Thank you, that makes sense, as even the 16 is marked reduced. I was kinda wondering as the PC revolver uses what appears to be a Wolff mainspring (they look the same) and I wondered whether the PC may have used a lighter rebound spring.

Bill, small world. I am a Surveyor in north central NM. Scratching my head trying to remember whether we have crossed paths. Looks like Snoopy needs to stand on his doghouse to see through the transit. Lord knows I have stood on "stuff" to see through my gear at times ;^).

Thank you both, looking forward to spending time here.

Craig
 
Why not use some blue lock tight on the stain screw, back it out to where you want it, and the lock tight will hold it there, I do it all the time. If you do that you can always return the revolver to original if you want to.
 
Bearbait in NM said:
The second question is after setting the rebound, and adjusting the main. My plan was to back the strain out in increments, test against CCI primers, and note the final weight that I want. I would then dress the screw head down to get that weight with it seated tight. Does this sound reasonable?
Click to expand...

This is the way to do it, by counting revolutions of the screw backed out the, plugging it into a formula to convert revolutions to inches based of the pitch (which I forget right now), then filing the strain screw down. You can play with the arch in the mainspring but it's less straightforward.
 
S&W trigger weights

Disclaimer: I'm old and haven't worked on any new S&W revolvers; however, I'm old and have worked on many older (1960-1970's) S&W revolvers. I was taught never to mess with the strain screw or mainspring. All the weight for a single action/double action trigger adjustment can be accomplished by changing only the trigger-rebound spring. I've set my K38's to two pounds for casual target work simply by changing that spring (and maybe a little light stoning on the rebound-spring block. When I was young, all the old guys always stressed leaving that strain screw all the way in and not messing with the main spring tension. J.
 
Thanks again all. Retired, I have no problems with loctite in general, my thought is that as I usually take the grips off when cleaning, I like the idea of just throwing a screwdriver on the screw, and giving it a snug.

John, that is interesting. Again, I have not been able to come up with a copy of Kuhnhausen yet, but the rebound spring is going to be my first change. I would never fiddle with the spring, as I now have spares, and I like the idea of just swapping out to a new spring when what is in the gun gets tired. And that ties into either dressing the strain screw or possibly shimming, rather than loctitie. I originally thought the rebound would not affect SA pull, but upon more reflection perhaps it will. I am only looking for a pound in SA and perhaps two in DA.

In any case, my box from Brownell's arrived, so I do have some things to try now.

Craig
 
trigger spring

Bearbait.... the trigger rebound spring is THE spring that controls the weight of pull on the trigger...Just put anyone of the new Wolff reduced power springs in your gun you will feel the difference in both single action, as well as double action weight of pull. If you have some good action 'stones', a light dressing of the block that houses the trigger rebound spring will also make a shocking difference. Pls. let me know how you did with your 'action job'.... J
 
John,

Thank you. That does make sense, although there does appear to be differences in the main spring. My PC gun came with a ridged mainspring that looks suspicially like the one that also came in a Wolff action kit. My problem is that this is my only S&W revolver, so I am not sure if my main is different than what ships on others.

YES, I will absolutely update this thread. You all have been great. Got sidetracked this week, and will be derailed this weekend, as well. My plan is to methodically change things out, record everything on my trigger guage, and report everything. About all I have been able to do this week is dry fire the heck out of it, now that I have my snap caps. Thinking that I want things on the gun "settled" in a bit, so the dry firing is probably a good first step.

Craig
 
trigger

Good thinking on the dry firing... Certainly will help provide a good baseline. I don't know about originality of your main spring; haven't ever opened a newer S&W. GOOD LUCK and enjoy the project, I know I always love to tinker. J
 
I have used the Wolfe reduced power spring and have mis-fires.
I now have a Wilson reduced power spring, reduced rebound spring, some polishing and now have a 7 lb 8oz double action trigger pull on my 625-8.
You will need to use Federal primers in your reloading. They are the softest primers on the market. By the way the screw for the hammer spring is locked down and NOT backed off at all.
 
OK, was up late last night, getting some numbers. I'll start with the specs.

625 PC s/n CUZ05xx (supposed to be new on GB, looked new but it could be older but unused)
Firing pin 0.490 in length, went ahead and chaged out to .510 C&S
Hammer main is ribbed with curved forks at top

Here are weights as averages of at least 6 pulls with my Lyman
(weights are in lbs and decimal oz's, DA then SA) gun mounted in a vice trying to be very repeatable with guage technique:

Stock: 11 11.2 /// 4 6.2
Strain out 1 Turn: 9 10.0 /// 4 1.0
Strain out 1.5: 8 8.2 /// 4 0.1

Wolff 15 Rebound: 11 7.8 /// 3 5.2
15, 1/2 turn out: 9 9.0 /// 3 6.3
15, one turn out: 8 11.7 /// 3 7.1

Wolff 12 Rebound: 10 15.0 /// 3 11.1
no further testing, as trigger return was terrible at 12.

My thoughts. I thought the return spring would be more dramatic as to weight change v. pull weight. Gonna try to stay with 15, as the return feels good. I did try a replacement M25 strain screw (blue) but it was well short of my stock SS. Gonna stay with the Wolff stuff, as I also now have a new Power Rib 2 to recheck as above, and an additional spring set. Not gonna dress on my stock strain until I can get a correct spare. And I need to find the minimums with all primers going bang, in clips and single loaded. Not gonna make the gun brand specific.

Another thing I found out last night once I had my pull weight down to the three's SA, is that my overtravel trigger pin is very short. I could catch the sear break at least a 1/16th inch before the stop hit. I need to test more and perhaps address. I have quite a few guns on various platforms with stops, and this one seems incorrect, even allowing for some safety margin.

Craig
 
trigger springs

Craig, from the info on this Jerry Miculek video, and from Blue Oval Bandit, I stand corrected re: adjusting the strain screw/main spring along with the rebound spring.. hope this video helps (there are also some other videos on You tube that are specific to the 625, but this is THE MAN working a mod 10.... How to install a spring kit (trigger job) with Jerry Miculek - YouTube.... John
 
John,

Thank you and I had looked at that video. His tip on using a BIC pen to reset the rebound and spring was pretty handy last night ;^). That video was part of my reason for asking my initial questions, and confirming methodology.

Not saying that I do not trust JM on his approach, but much like what was probably correct back when you were smithing, "accepted" techniques probably evolve with time, and use for the gun. The old competition v. carry/duty in particular. I did not miss Blue's post, but I would be concerned about doing the math for a final cut. I am thinking I will either use loctitie or shims under the screw head, and dress the tip at the range while confirming ammo and my trigger pull guage. Leave myself the ability to lower the screw just a bit to account for wear in the mainspring.

I hope my numbers post above kinda helps show that there are a couple of ways to skin the cat, combining the rebound and main. I was surprised last night while fiddling with both how much different the gun could feel. Not just light, but including the rebound. I knew right away that the 12lb rebound felt awful, with such little rebound action. And the 12 bought me very little on the overall weight.

Thanks again,

Craig
 
what i did 30+ years ago, when playing with the actions, was to apply automotive valve grinding compound liberally to the action and sit and dry fire a zillion times. i would then open it back up and look for the bare or thin areas of compound and thusly concentrate on them with more compound and dry firing again.

smoooooth


..
 
Teezer,

Times have indeed changed. I think the preferred method today by the Cowboy Action shooters is to use toothpaste to do the same. And I think they are specific about it being Crest ;^) And Crest would be cheaper than JB Bore Paste......I got past my assembly panic last night when the spring fell out of the trigger, when removing the hand. I'm gonna address the innards after getting the spring weights sorted. And I did indeed ponder Crest or lapping paste of some sort. seriously.

Craig
 
I don't believe in dressing down the strain screw to lower trigger pull. I do all mine with about 2.5-3hrs of stoning with a fine India, Hard Arkansas, Ruby Stones and Spyderco Ceramics. I also make sure to de-burr surrounding parts as I go. I do make sure it will run CCI's as they are harder then most. also making sure the cylinder rotates with ease will help DA greatly.
 
i picked up a model 19 a few years ago and wanted a smoother action. ordered a set of Wolff springs that had 13, 14, 15# rebound springs in it, didn't like any of them. took the 15# spring and cut 3 coils off (remember to put the cut end in the block) and was very happy with the result. the strain screw remained tight.

i still would use valve compound over toothpaste as it's made for metal work, and way to many choices of Crest on the market


..
 
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