Trigger tuning for late model S&W's

SLT223 · #1 10-14-2015, 11:25 AM

I have a Model 620 and a 627-5 that's inbound. I shoot double action almost exclusively. I like shooting around 250 to 300 rounds per outing, which is about very weekend. The 620 trigger is killing my right index finger. I love the stock action, but I need less trigger weight to shoot the volume I do. As I type this I have a blister. What spring kit manufacturers would you recommend if any?

With some of my older guns I've simply cut down the strain screw to where the trigger produced about 10 pounds with the screw torqued down. I'm not beyond doing that again with the 620 and 627, just want to explore options.

walter o · #2 10-14-2015, 12:52 PM

I find that a light polishing of the trigger rebound slide, a lighter rebound slide spring and polishing the surfaces that the rebound slide rides on usually dramatically lightened the trigger . look at some of the u-tube vids. and polish don't remove metal. Wolf sells a shooters pack with several weights of springs .Its a trial and error to find the correct spring wt. for your gun usually a 13 # spring works well in mine .
If it is only a target gun you can lighten the hammer spring.If it is used for personal protection I would not lighten the hammer you could get a light hammer strike when you need it the most.

gwpercle · #3 10-14-2015, 01:09 PM

Clark Custom Guns, for $115.00 they put a service action trigger job on a model 64 S&W and it's the best value I have spent money on.
That's after me buying springs and kits and trying all manner of things that turned out to be less than 100% reliable. The gun fires every time the hammer drops and is as smooth and silky as a baby's bottom.
They also do target trigger jobs, have one on a Ruger MKII and it is a lovely thing to use. Makes my S&W model 41's trigger envious , it wishes it was as smooth and light.
The trail and error spring thing turned out to be a pain in the you know, I couldn't get light and reliable , then found out about Clark's....Oh Yeah, that's the ticket.
Gary

Laketime · #4 10-14-2015, 01:12 PM

The best action job only requires the honing and smoothing of the lock work.Lighter springs is the wrong way to improve an action.You never experience hammer off condition with a factory action improvement.

tomcatt51 · #5 10-14-2015, 01:46 PM

This was about the 625 but it's a good discussion and it all (except the chamber reaming) applies to your 620 and 627.
625PC Hammer weight Adjusting

SLT223 · #6 10-14-2015, 02:09 PM

Thanks all! The action is plenty smooth for my liking, just a little on the heavy side for 300 round sessions. Definitely needs to be lighter. I really appreciate everyone's insight.

tlay · #7 10-14-2015, 08:14 PM

When I do any trigger jobs I smooth all surfaces related to the trigger and hammer. Take everything out and first smooth the frame area contacted by the trigger return. I also smooth all sides or the trigger return and install a 13# spring. Next I install the trigger on my stoning fixture and barely touch the sears with the ceramic stone. I polish all contact surfaces and oil everything and reinstall. I can get a reliable 8 or 9# double action.

Goblin · #8 10-15-2015, 01:18 AM

Have you considered rounding the trigger, or has that already been done?

gnystrom · #9 10-15-2015, 10:05 AM

Post 7 & 8 have it nailed.

SLT223 · #10 10-21-2015, 06:50 PM

Quote:

Originally Posted by walter o

I find that a light polishing of the trigger rebound slide, a lighter rebound slide spring and polishing the surfaces that the rebound slide rides on usually dramatically lightened the trigger . look at some of the u-tube vids. and polish don't remove metal. Wolf sells a shooters pack with several weights of springs .Its a trial and error to find the correct spring wt. for your gun usually a 13 # spring works well in mine .
If it is only a target gun you can lighten the hammer spring.If it is used for personal protection I would not lighten the hammer you could get a light hammer strike when you need it the most.

Well, this was the route I went because the trigger was already smooth as glass and I just needed it to be lighter. WOW! I have what feels like a completely different gun! The Wilson main spring and 13# return is PERFECT!!! This was exactly what I was looking for. Thanks much for the advice!

garbler · #11 10-21-2015, 08:04 PM

You're a serious shooter who's working double action and need a serious gun. I can tell you right off you need a 6-8# DA pull and one that cycles without any hitches or surprises in order to achieve the kind of performance I think you're looking for. Secondly you need a personalized shaped and polished trigger and grips that fit. Then as long as the gun groups and has a real action job you'll be a happy shooter

A true action job is not a spiring swap and polished rebound slide. The lockworks on these guns is a parade of parts all of which have to properly interact to provide the shooter with real double action performance. Each part can contribute a 1/2 oz to as much as a pound of friction and resistance. This accumulation of tolerances is what equals a hard lumpy double action pull from the factory. A good mechanic treats every part much like a race car engine builder blue-prints an engine. There is no free lunch and those who swear they bought an action job from Wolf are fair game for these merchants

Regards

garbler · #12 10-21-2015, 09:54 PM

Quote:

Originally Posted by tomcatt51

Your DA pull has to:
Overcome the hammer spring and rebound spring.
Overcome the friction of the parts moving.
Overcome the inertia of the loaded cylinder.

The mainspring has to:
Have enough tension for reliable ignition for your situation. What's enough for hand seated Federal primers won't be enough for CCI primers less than fully seated etc.

The rebound spring has to:
Return the trigger.
Move the hammer back near the end of the trigger return.
Reset the cylinder stop near the end of the trigger return.
Push your trigger finger forward if your DA technique is poor and you don't get your finger off the trigger as soon as the hammer starts falling.

So we lighten springs and reduce friction.

We bend stock mainsprings or use re-arched mainsprings that maintain optimal hammer strut/link geometry with lesser preloads.

We lighten hammers so we can run lighter mainsprings while maintaining reliable ignition.

Mainspring weight/preload affects trigger return because the hammer is moved back by the rebound slide near the end of the trigger return. The rebound spring supplies the energy to do this and to reset the cylinder stop. More mainspring requires more rebound spring to overcome it.

We rework the "ramps" on the rebound slide and hammer that move the hammer back during the trigger return so a lighter rebound spring can do this.

We rework the trigger / cylinder stop surfaces so a lighter rebound spring can reset the cylinder stop near the end of the trigger return.

The cylinder stop reset occurs last during the trigger return. The hammer moves back before the cylinder stop reset occurs.

There's a bunch more but maybe this will help without being too much to digest... As garbler said, it all adds up.

Here is a real mechanic whose just outlined most of the steps to a real action job. But if you were a little birdie on the wall watching him you'd be on page four writing all the other steps between and beyond. Despite what many may think gunsmithing is a skill and trade and not all who come out of the schools are good anymore than everybody you graduated with got all A's and B's.

Regards

SLT223 · #13 10-22-2015, 07:43 AM

Much appreciated Tomcatt. I'm pretty mechanically inclined as in I build my own motors, transmission, computers, etc... I think I'd like to give the whole process a shot. I think a late model revolver would probably be a good starting point since parts are readily available if massage any of them too much.

Would brownewlls or midway have most of what I need? Where else should I look for gunsmithing tools?

Also, when we talk about polishing surfaces on the parts and the frame what grit is used? I'm guessing north of 2000 for finish work?

Taj · #14 10-22-2015, 04:44 PM

Main spring weights will vary hugely on S&W revolvers. I worked for Smith and have worked on Smiths since John Contro was doing the LE armorer's course way back when. The accepted minimum requires the hammer/mainspring to lift 3.5# for reliable ignition. When we would do a "factory tune" we'd cut the strain screw to achieve this, and put in a blue model 14 SA rebound spring. Of course the lock works were smoothed to get reliable rebound. I found this to be a reliable combo for service guns and never had one come back for a failure to fire with factory ammo. I still have guns that were tuned that way over 30 years ago and still remain reliable today. Of course I have PPC guns that won't lift 2.5#'s but they are target guns dedicated to shooting factory Winchester wadcutters.

wayne_i · #15 10-22-2015, 10:28 PM

Jerry Miculek also sells a kit. He also has videos on line to help explain how to smooth out the trigger, set the pull weight (along with suggestions), and has a kit for K,L and N frame revolvers. I have installed several of these and they work very well (including the later models with the safety). Since Jerry is the world champion revolver competitor and is on the S&W shooting team, I think he knows what he is doing too. His web site is jerrymiculek.com. Hope this helps. Wayne

48Blister · #16 10-24-2015, 04:01 AM

Yeah what he said.

blackcloud45 · #17 10-26-2015, 04:08 PM

I used this DVD:
Jerry Miculek's S&W Action Job - DVD [MIC-X0201D] - $19.95 : Team Miculek - The Legacy Lives On

and this spring kit:
MIC-625 Miculek S&W Revolver Spring Kit K, L, & N Frame [MIC-625] - $16.95 : Team Miculek - The Legacy Lives On

w/ these stones:
NORTON 6" X 1/2" X 1/2" INDIA STONE | Brownells

and this gauge:

ELECTRONIC TRIGGER PULL GAUGE | Brownells

to tune up my 686+. It's night and day. Double action is smooth and easy to shoot. Took a 3 day class with this gun and didn't have a lick of trouble.

Gunhacker · #18 10-26-2015, 07:13 PM

To add my $.02 worth... typical discussions of this nature usually run towards what's done on guns with the older style firing pin on the hammer, and little or no mention of dealing with the new frame mounted firing pin and spring.

The Jerry Miculek "Trigger Job" video, which I have, uses the older style gun too.

With the new style guns with the frame mounted firing pin and spring, you have another aspect that comes into play in tuning the DA pull, and that is being able to use one of the extended length firing pins (or in the case of the APEX, the XP firing pin kit, which is an extended length pin paired with a reduced strength firing pin spring), to ensure prime ignition with the lighter hammer strike that results from either using a reduced power mainspring or shortening the strain screw to back off the tension.

One of the biggest buy backs I got from Jerry's DVD was the process on how to reduce the spring tension of the bolt on the cylinder center pin, allowing it turn a tad more easily. As the "Man" says on the DVD, it's a bunch up little things that all adds up".