625PC Hammer weight Adjusting

[Pdxrealtor]

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.

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?

 

[tomcatt51]

The only caveat is that hammer weight could be light enough to allow these sub-12 pound springs.

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.

 

[Pdxrealtor]

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

 

[tomcatt51]

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?

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.

 

[Pdxrealtor]

Is your 617 hammer clipped?

 

[tomcatt51]

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

That's doable. Read the thread.

 

[tomcatt51]

Is your 617 hammer clipped?

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.

 

[Pdxrealtor]

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.

 

[Pdxrealtor]

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

 

[tomcatt51]

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.

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

 

[Pdxrealtor]

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.

 

[tomcatt51]

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

 

[Pdxrealtor]

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?

 

[tomcatt51]

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.

 

[Pdxrealtor]

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

What am I missing?

 

[tomcatt51]

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...

 

[Pdxrealtor]

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.

 

[tomcatt51]

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.

 

[Pdxrealtor]

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)

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.

 

[Pdxrealtor]

PS - thanks for all the continued advice.