Smith Revo Light Strike


PDA






PKAY
March 16, 2003, 08:20 PM
I recently bought a consignment 625-6 in pristine condition though used. It had been highly polished by a very patient and dedicated former owner. The action was light and smooth, which led me to believe the owner performed or had done a nice action job. I bought a bunch of full moon clips and loaded 'em up prior to going to the range. Once there, it took about 100 rounds before every load of six would exhibit at least one light strike and non ignition in DA fire (no problem in SA mode). After about a dozen light strikes in as many full clip loadings, I packed up and went home.

I thoroughly cleaned the piece and then disassembled it. Guess what, folks? Besides MIM hammer and trigger (my first experience with MIM parts), it appears our former owner achieved his "smooth action" by backing off on the mainspring strain screw using some sort of goop to keep it from backing out further on its own. In addition, about 1/3 rd of the rebound spring had been summarily clipped off as well. I completely disassembled the gun inspected, cleaned and lubed the individual parts as well as polishing the bottom and back of the rebound slide (per Kuhnhausen's instructions). I left the arm disassembled and ordered a set of lighter power springs from Wolff. Got 'em yesterday and reassembled the gun. WHAT A DIFFERENCE! I'm sure the light strike problem was from the strain screw having been backed out. We'll see. The new mainspring is down tight with the strain screw all the way in and the rebound slide is sporting a longer but 13 lb spring. It cycles beautifully in both DA and SA. BTW, the MIM parts sure seem "cheezy" compared to the old style. The action seems to function well with them though.

Any thoughts on these matters?

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HSMITH
March 16, 2003, 11:00 PM
You did the right thing in putting it back closer to original. Strain screw trigger jobs ought to be an arse kicking offense IMO. Springs and such as delivered from S&W can provide amazing trigger pulls. Heavy does not hurt anything as long as it is smooth. Do your part, improve the mucles needed for DA shooting and go back to bone stock on the springs or at least stock weights. Reliability problems with stock weight springs just don't exist.

Jim Watson
March 17, 2003, 12:40 PM
Ammo?
US brass cased factory loads or good reloads with well seated Federal primers fire easier. Many imports, Blazers, and other primers, especially CCI, are harder.

Cylinder & Slide makes a replacement firing pin .015" longer. Maximum firing pin protrusion that does not pierce primers will fire with a lighter mainspring.

If all else fails, get a stock mainspring. My old M25-2 requires a standard mainspring and a primer cup as a shim under the tip of the strain screw for reliable ignition. I think the gunsmith ground the strain screw down and I could not find a replacement when I realized the problem. It worked with the shim so I just quit looking for a new screw.

Do not use such a soft rebound spring that your trigger finger outruns the trigger reset. One revolver shooter here has as light a mainspring as will fire Federal primers with a long firing pin; but he has a stock rebound spring. He says he likes the feel of the trigger pushing his finger forward to reset.

Standing Wolf
March 17, 2003, 11:20 PM
...about 1/3 rd of the rebound spring had been summarily clipped off...

I've been known to chop off as much as two coils, but a third of the rebound spring? It's a wonder the trigger reset at all!

I often lighten the main spring a little by backing out the strain screw 1 to 1.5 turns—but I make very sure it still delivers enough power to the hammer.

I knew a fellow years ago who swore by drilling small holes in the main spring. As far as I was concerned, he was risking breaking it under repeated stress.

Jim K
March 17, 2003, 11:43 PM
If you back the strain screw out too far, the tip of the mainspring will contact the bottom of the hammer and actually increase the trigger pull. If you must reduce the mainspring, grind metal off the sides (not off the flats) and leave the strain screw alone. I never heard of drilling holes in the mainspring, and agree that it could be asking for trouble.

Taking 1 1/2 - 2 coils off the rebound spring is a common practice when working over the trigger, but here again, rolling the spring on a belt sander can do the same without shortening the spring.

One note, though. Manufacturers design their guns to work under adverse conditions like cold, heat, mud, dirt, hard primers, poor ammo, etc. They use heavier springs than necessary to try to ensure that functioning. A "trigger job", no matter how well done, reduces that margin of reliability. Some folks try to get a gun, even a carry gun, down to the "super smooth but barely functioning" level. That could put the shooter in the "not functioning at all" category.

Jim

Jim Watson
March 18, 2003, 12:23 AM
There is a limber spring set for SAAs that has a mainspring with a slot right down the middle. Well rounded ends to avoid stress risers.

Skeeter Skelton once showed a picture of a S&W mainspring he had edge-ground to reduce its strength. Wish I still had the magazine, but I recall he kind of necked it in just under the hooks for the hammer stirrup, tapered it out toward the bottom pretty much parallel to the original profile, then necked it back out to full width where buried in the frame groove so it wouldn't walk around.

Standing Wolf
March 18, 2003, 08:18 PM
Skeeter Skelton once showed a picture of a S&W mainspring he had edge-ground to reduce its strength.

I'd be afraid the heat from grinding would alter the spring's springiness and/or weaken it.

I sent a Python to Cylinder & Slide for an action job, and noticed the V main spring had been reshaped and heated. I trust the good folks there know what they're about, but hadn't ever encountered the technique before.

Jim Watson
March 19, 2003, 10:48 AM
You have to grind a spring slooowly, with frequent dunks in water, to avoid overheating. If it is too hot to touch it is too hot. As Jim K says, you can even grind down a coil spring. Dale Rhea, the Glock wizard, gets some wild shapes on his recoil springs rather than replace them with non-Glock springs.

I don't know about heating, the usual method for reshaping the Python mainspring was once to stick a 1911 firing pin through the V and cock the hammer. My Colt Custom Shop gun does not have the "raftered" spring, but all the guns around here that the local 'smith copied after mine do, in addition to the reshaping of the trigger's DA contact area. They all need Federal primers, though.

bountyhunter
March 19, 2003, 03:14 PM
Before you shoot everybody who dials out the strain screw and trims RB springs, I must confess you are describing my 686 comp gun. It allows me to get the lightest DA pull (about 5.2#) and still fire reliably and get good trigger return. The real crime here was in selling a tweaked gun to an unsuspecting person. Such a gun is only for the fanatical fiddler who likes to tweak them. To get it 100% reliable, you did the right thing: get a matched spring set and crank the strain screw all the way in tight.

As for your comments on MIM: I agree. They seem to work OK but are baboon butt ugly. The surfaces look lumpy, bubbly and uneven.

One note on this:

"I often lighten the main spring a little by backing out the strain screw 1 to 1.5 turns—but I make very sure it still delivers enough power to the hammer."

I have done this a fair amount, and I have found that for stock SW mainsprings and strain screws, it's not a good idead to go past 1 turn... and I would recommend about 3/4 to 7/8 turn maximum. Use blue Loctite on the screw so it doesn't wander any farther out. BTW: The new guns with frame mounted firing pins take a bit more force to fire reliably.

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