Final update, with some interesting results.

I scrounged up a .495 S&W titanium fp, and an 11 lb rebound spring. Did a lot of testing today, with some very good and useful results.

First, my major error. Earlier on, I noted going to hammer shims. I figured getting all of the play out of the hammer would be good. Later in the thread, I noted having to go back up a little higher on the poundage, to get reliable ignition. When I was installing the new FP, I checked the hammer play. With the gun a bit dirty, the hammer was dragging a little when tested loose. I took out one of the 2 .002's on the left side of the hammer. I should have accounted for dirt tolerances when shimming.

Today, all DA, testing the s&w .495 firing pin and 11 lb rebound with an Apex firing pin spring (which feels lighter than the s&W stock spring) I was able to get down to 7.5 pounds before seeing an occasional light strike on winchester primers, seated in very mixed brass, seated on my Dillon. The high ones would go bang second time around. No issues with CCI's hand seated. And when I say mixed brass, talking Amerc junk and lots of mystery headstamps. With Winchester brass, Dillon seated winchester, no issues.

I then got creative. As my gun will correctly headspace and fire without moonclips, I tested a bunch of this mixed brass high primer stuff sans clips. Got down to below 7 pounds with no issues. I did not test lower, because 7 really felt bad to me. It felt "too light". Hard to explain, but that is what I felt. The 11 lb return is also right on the edge for me.

What this seems to be saying to me is that there is a relationship between the moon clips and trying to get really light. If below 7 works without clips, and it takes 7.5 or so with clips, there must be some loss with the firing pin having to move the clip mass forward in some situations. In trying to save some ammo today, I only tested TK clips, and nickel ones that I think are Wilson. I have a couple of other brands that are terrible with mixed brass. Probably worth trying some different brands if going really light.

I tested the Apex .495 and Apex spring earlier, and I think the stock S&W titanium is the way to go, if you can get a .495. Mine came stock at .490. Either going with the Apex spring, or perhaps a clipped s&W firing pin spring sure seemed to help.

I did not test out any of my AR brass today, but based on the behavior of the non-clipped mixed brass, thinking the AR should allow for some really light numbers. I am going to set mine up at 7.5 to 7 3/4 and call it a day. With the smoothed up internals and weight at this level, the gun feels stunningly wonderful, compared to the stock 12 lbs.

Thanks to Tom and the others here who have helped me so much.

Craig

Adding a shim on the hammer stud. That sounds like what I need. Are they available precut or do I need to make one? Thanks

Power Custom Hammer Sideplate Shims S&W K L N-Frame .002 Package of 10

I have three 627s 2 - 38 supers 1 - 357 and one PC 625 and a 1990 vintage 625. All five revolvers have double action trigger pulls right at 4 1/2 lbs. they are 100% reliable as long as I use Federal Primers. The mainspring has been slightly reduced in width. The strain screw has not been touched. The balance of the action work consists of reduced power rebound springs and polishing of the interior of the frame and hammer.

Great info here guys. I'm left a bit confused on the firing pin selection.

I have the .495 S&W firing pin. With a 13# rebound spring and stock main spring set via strain screw being backed out I had to go up to 8 lbs to get reliable (actually just beginning stages of reliable).

My next move was going to be the C&S .510 firing pin as I've read this is a good solution. Is it not? I'm working with a 386 night guard, L frame, .357.

Thanks again for all the great info in this thread.

The C&S is NOT going to help. Keep the .495 S&W pin.

With a 13lb rebound spring I would expect you to have an 8+ lb pull to get reliable ignition. A lot of the work we do is getting the trigger to have a good rebound with lighter rebound springs. After removing any hammer drag and getting a mainspring/strain screw set that gives reliable ignition (much of) the rest of the work is getting a good trigger rebound with the lightest possible rebound spring.

Ultimately how light you can go is based on the mainspring. That's why we lighten hammers and use hand seated Federal primers, so we can run less mainspring. Rebound is balanced against mainspring.

Thanks, Tomcatt, for the confirmation.

Two Questions:

1) What is the length of the strain screw from S&W. Mine appeared to be ground down already, and I went too far in taking it down farther. (Shoulda got the calculator out).

2) My 386NG has the 'mid target' hammer pictured below. What method of lightening removes the most weight? Trimming the sides, drilling several holes, one large hole, or ?

Spur width:

std = .265"
semi-target = .375"
target = .500"

I was going to have it trimmed anyways. Now that I'm into this thing I'll just do it myself.

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Couple of observations take them for what they're worth to you

1. Hammer shims are not always drop in parts. At least 50% of the time you have to face off or remove a bit of the stud's boss on older models or riding surfaces on the frame or side plate to center up the hammer. It's trial and error fitting. Once done correctly you should have a perfectly centered hammer without any real side play.

2. Claiming a 4.5 pound DA pull on N frames or L's for that matter with reliable function is very hard to believe. I'd have to wonder how this was measured.

3. Installing a 11 pound or lighter rebound spring is asking for trouble down the road. This is the kind if thing that could cause an accident because some well intended shooter may not understand why the heavier factory spring was there in the first place. These light rebound slide springs can be marginal or too weak to set the hammer on the hammer seat --that elevated knob on top of the rebound slide. That and the hammer block are the only two safety features on these guns. The rebound slide has to have enough push to force the hammer seat up into position which in turn pushes the hammer face off the frame, letting the block slide in and making it impossible to accidentally hit the hammer and fire. So installing too light a rebound spring, looking for a quick and easy action job, and you can easily negate the major safety feature on your gun. Understand the more use the gun sees the more wear the spring and parts get and of course any accumulation of residue can make the lockwork sluggish.

Secondly reduced power springs will in fact slow down your DA trigger recovery time. I personally will tolerate an extra pound on the SA if it's creep free but not a balky slow DA trigger that if you're not careful will lock up the gun temporarily. I guess it depends on how you shoot your guns but my love has always been the fact that no other revolver can be slicked up like a K or L frame DA and no other revolver has faster lock time. As a rule of thumb you should never go lighter than a 12 pound rebound spring for normal use. For fast comp shooting a 14 pound may be preferable but it's personal taste. 12 pounds will still maintain safety and reasonably fast trigger cycling if the gun is clean and healthy. The only caveat is that hammer weight could be light enough to allow these sub-12 pound springs.

Regards

1) They vary. I avoid the issue by using 8-32 (headless) socket set screws instead. Great range of adjustment but doing this is a sin according to some here...

2) .265s are the lightest stock hammers. I do everything from traditional bobbed hammers to drawing a line from the top of the hammer to just behind the pivot hole and cutting off everything behind the line. On an N frame MIM hammer that's a 50% weight reduction. It's amazing how fast that hammer falls with a stock mainspring and strain screw.

Good info! I pulled up a picture of my internals and see what you mean.

I watched my groups get wider and wider while tightening up the strain screw last night during reliability testing, so I'd like to go as light as possible down to the mid 7lb range.

That said, I want a reliable setup so will settle for a bit higher as a trade off.

1) Yes, I see you've mentioned the headless screw and Loc-tite 290 more than once. That's my plan. I'll make it part of the cleaning routine to check the screw. But what is a good length to start? Guess I could just measure my current one and add a bit.

2) I should have added I want enough hammer to cock the gun easily. I'm thinking a big hole through the middle of the spur would be the most efficient?

And that's how it's done, along with hand seated Federal primers. They're not cosmetically pleasing but my competition MIM N frames have hammers that are literally half their original weight. The lighter the mainspring is the lighter the rebound spring can be. The mainspring (and the geometry of the hammer and rebound slide "humps") mostly determine how light you can go on the rebound spring.

I've had my 625-8 running at 4 1/2 lbs. Lyman digital gauge with the roller sitting where it wants to in the trigger curve and the rod running parallel to the barrel. I really didn't like it at that weight. May have been a matter of getting used to it. My centerfire K & N frames are all in the 5 1/4 to 5 1/2 lb range. Wolff 11 lb rebound springs with 2+ coils clipped are the norm.

My favorite 617 runs some ammo at 7 lbs and fires pretty much everything at 8 lbs. The difference is just a twist of the strain screw. The same clipped 11 lb rebound spring works at either pull weight.

There is a bunch more involved here than just dropping in springs and there's a spring difference with different hammer weights and in setting up a gun to run any ammo vs one built for just hand seated Federal primers.

I'd be happy at 8lbs and ability to fire any ammo

Just trim the spur down close to hammer thickness and then trim the length. They really don't need a lot of spur.

It all counts but weight removed farthest from the pivot does the most good.

Is your 617 hammer clipped?

That's doable. Read the thread.

NO!!! It's a 617-1 with the old (heavier) forged hammer. Rimfires you build differently than centerfires. You don't lighten the rimfires' hammers.

That came out wrong. Sorry about that. I went through a couple cylinders at 8lbs with 100 percent success last night. I ran out of time then botched the strain screw.

Oops.... Should have looked before I spoke. Didn't know the 617 is a rim fire.

That's great. Lots better that the 11 or 12 lb pulls they usually start with.

Certainly. Just need to run more ammo through it. I'm lucky in that I have a pile of Freedom Munitions that FTF. Buffalo Bore FTF once on me too.

Need more time. I think the game plan will be to put the Wolff stock weight main spring in, adjust the strain screw for 100% reliability then swap out the 13# main spring for a 12 or 11# and see how it feels.

If I can't get low enough I'll trim the hammer.

Who am I kidding. I'll likely trim the hammer before my Wolff main spring shows up.

I use Wolff reduced power mainsprings and socket set screws as strain screws. On some I narrow them slightly.

With 100% reliability?

It seems it's six of one half dozen of the other. Loosen the standard Wolff, or tighten the light Wolff.

No?

No. I use the Wolff reduced even on 7 1/2 lb shoots everything guns. The reduced power springs get a bum rap because people use too short a strain screw with them. They can require a longer strain screw. This where the socket set screws as strain screws are nice, range of adjustment.

It's a geometry thing as is the reason you don't use std springs with short strain screws. You want to end up with an installed spring that looks like an installed stock spring in terms of arch. You want the hammer end of the spring in the right place so the hammer strut or link is at the correct angle.

A really nice light DA pull is the result of a lot of little things being right.

The longer strain screw just puts more tension on the spring, increasing the arc.

What am I missing?

Geometry. The spring with more (static) arch needs the strain screw screwed in farther just to contact the more arched reduced power spring. Plus there's the rib the screws' tip sits in.

Go back thru this forum and you'll see lots of "the reduced power spring gave me light strikes". Yes, with the same strain screw they can but getting these guys to go with a longer or (heaven forbid!) non-stock strain screw was/is a "bit" difficult. It was always that damn reduced power springs fault... they're no good...

Let me see if I'm understanding.

The reduced power Wolff main spring has more arch than the standard weight spring thus causing the OEM strain screw to not contact the main spring as Wolff intended?

Therefor a longer strain screw is needed?

In any event it seems you're saying that with the reduced power main spring and longer strain screw in the end you'll end up with better geometry than the standard weight spring and a bit shorter strain screw.

Because, no matter the spring, one will need to end up with the same pull weight to get the reliability. IE standard weight main with shorter screw or lighter weight main with longer screw.

We're kinda going in circles.

With the side plate off slowly unscrew the strain screw and watch what happens at the hammer strut/link end of the main spring. Look at what the strut/link does, how it moves and its' angle changes. You'll see why you don't run a stock spring with a shorter or backed out strain screw.

I will do that...as I'm headed out now to trim the hammer...

but you just confirmed what I said above. (or below- I put in quotes)

PS - thanks for all the continued advice.

Hammer trimmed. I completely forgot to weigh it before and after, but I took a good amount off. Then polished it.

Hoping I get some benefits from this, but if not I planned to do it anyways for carry purposes.

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[QUOTE=Bearbait in NM;137683196
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?
[/QUOTE]

Yes, that is reasonable and is the way I do it. Also the way Jerry Miculek does it (I saw a video on his website). Be aware that double action will be the first mode to fail if you go too far in shortening the screw length. Also be aware that CCI primers are among the hardest available. Use Federal primers if you want to get a light trigger pull. They are softer.
I have found 13 pound rebound springs to be right for most of my guns. A 12 pound spring might make the trigger too slow to return. The trigger should follow your finger in fast double action shooting. You should not have to wait for the trigger to return to start position.

Quote:
"In any event it seems you're saying that with the reduced power main spring and longer strain screw in the end you'll end up with better geometry than the standard weight spring and a bit shorter strain screw."

Correct.

You need the reduced power spring for its' static arch, or you can bend the arch into a stock spring. A longer strain screw you may or may not need but a longer strain screw can be backed out or shortened. In any case it will give you a range of adjustment while setting your hammer fall for reliable ignition. That is where you start.

Rebound will be based on how much mainspring you have.

FWIW the difference between a Wolff standard and reduced power mainspring is just the amount of arch.

lol.... Tomcatt does light spring and tighter screw. Gets my mind made up, then you come along and completely spin my OCD brain. Awesome...



I ordered all the possibilities so I'll get it one way or the other. I'm tempted to go with the standard length and back the screw out a tad (a set screw not the OEM screw). But who knows. Right now I'm going to wait for the stuff to arrive from Wolff, and tune my gun with the OEM main, and a new set screw with a 13# rebound spring.

Any weight you remove is a benefit. More is better. Mine are all DAO.

Carry gun. I want the option to get in SA mode should I be in the back of a movie theater, cornered, and have the opportunity to potentially save mine and others butts from a distance. Or a like situation.

My j-frame is a 649, with the bobbed but cockable hammer. It's next on the tune up list. I'm really having fun with these revolvers!

Reread post #78. Have fun playing. It's how you learn.

I never had any luck with the Wolff power rib mainspring. It gave me light strikes. All my own work was with the factory mainspring and reduced strain screw length plus Wolff 13 or 14 lb rebound spring. You may want to grind one or both ends of the rebound spring flat. The factory spring is flat on both ends. It makes it much easier to install.

Reduced weight or standard weight?

That sounds sooo familiar. See post #76.

Wanted to give an update - I got the Wolf reduced weight mainspring in, and the 12# rebound spring. Used a hardened 8-32 set screw with a self made notch for reference.

As shown above I've removed a good amount of hammer spur.

Went to the range last night and had immediate failures in the low to mid 7 lb range.

Gave the mainspring screw a 1/4 turn and continued through 50 Freedom Munitions, 14 WWB, 14 Buffalo Bore, and 14 Barnes bullets. I had one failure to fire on a Buffalo Bore. I'm chalking that up to a random until I can get another one to fail. I won't be carrying the BB anyways as I prefer the Barnes all copper bullet and better ignition it's known for having

The pull weight in DA is 7 lb 12 oz - 7 lb 14-oz. SA pull weight is 2 lbs 5 oz every single time.

I thought about the 11lb rebound spring, but I'm not sure about the safety issues mentioned earlier in this thread. I'll likely leave the 12 lb spring in unless I can be convinced otherwise.

I did some rapid fire and the trigger keeps up no problem. A side from that I don't know how to balance the pull / rebound a side from feel. It feels OK to me. Better than my worked over CZ handguns as a matter of fact.

One last thing I did was go over the top of the trigger hook, and down around the radius, with some 1500 grit, and also lightly on the DA piece connected to the hammer that rides on that surface.

I had a slight 'bump' or 'increased pull weight' in the last portion of the DA pull that was either a result of the main spring geometry or the lack of polishing above mentioned parts. Likely the latter....

In any event the pull is simply fantastic now. No variation from beginning to end, and very predictable break with no added weight just prior to the break.

I'm open to any suggestions on going to the 11# spring or staying where I am now.

Also open to suggestions on some factory ammo known for tough primers.

This thread has been an excellent source of information. I hope my additions combined with others will help the next guy do this correctly. It is so very worth it!

Try one. See how it feels. If it doesn't work with what you've done go back to the 12 lb spring and you'll have learned something and lost nothing.

My 7 1/2 lb "fires everything" guns use 12 lb rebound springs. My lighter, 5 1/2 lb guns run 11 lb springs with coils clipped. My 617 (rimfire) at 7 - 8 lbs runs a clipped 11 lb rebound spring.

I'm more concerned about the safety issues RE: the rebound slide that were mentioned earlier in this thread.

If I understand correctly, the 11 lb may work fine now, may not. Or, it may work fine now but after some wear cause safety issues.

Only thing that would help with this is a lightened hammer. But how do I know if my hammer has been lightened enough?

Am I understanding correctly?

If the trigger resets, the hammer is back and is on its' "hump" on the rebound slide and the hammer block is in position. To get really light DA pulls we devote considerable effort to ensure the trigger resets with light rebound springs. The gun can't be fired again until it does reset.

Fact is, after firing the gun you have a fired case under the firing pin until you cock the hammer or pull the trigger again. The only "trigger reset issue" is that you can't fire the gun again until it does...

Of course there are those who insist the sky will fall... there are also many who insist replacing the original strain screw or not having it "fully tightened" will also cause the sky to fall...

Your gun, you decide.

Not trying to play "Chicken Little" here, and it is "your gun", but it seems a rather reckless course of action to pursue conditioning and reconfiguring of internal parts and springs to the point that can only be catagorized as "experimental", particularly on a revolver that will be used as a "carry gun".....if I read the earlier post correctly, something about you wanting to preserve the hammer spur so that you could shoot SA in a hypothetical scenario in which you were "in the back of a movie theater, cornered"?? (#86)

Sounds like a prescription for a possible accident in the making....owner produced internal modifications including a 12 pound (or perhaps 11 pound) rebound spring and a sub 2.5 pound single action trigger pull in a carry gun?

In an all DA range gun? Perhaps.

Safe, reliable and suitable to be utilized as a carry gun?

Yikes

__________________
Ret. LE, FA Instr, S&W Armorer

Have to say I agree about the SA pull on a carry gun. The light SA is a by product of a light DA pull. I'm not convinced a nice crisp 4+ lb SA pull with no take up is good in high stress situations either. I "fix" this by bobbing hammers and making them DAO. Makes them much harder to make a mistake with...

CZ has shops that sell complete kits for carry guns. They place the DA/SA pull at mid 7 and mid 2 lb range. Maybe that's abnormal..... I don't know.

That's a semi-auto - shoot it once and it defaults to SA mode. A revolver has to be cocked.

Just saying....

I need more range time with different kinds of ammo as well.

A SA semi-auto trigger has some take up before engaging the sear unlike a revolver which (after you make the mistake of cocking it) has none and any trigger movement is a bang. It's very unforgiving under stress unlike a semi-autos trigger with take up before break or the relatively long pull of striker fired guns.