Model 10 light hammer strikes

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CarlJ

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We went and shot the model 10 and the 642 today. We set up the target at 25'.
Shooting Aguila 158 gr HP. This ammo was good and accurate, a tad dirty but not real smokey.
This model 10 is a police import. I haven't had it taken apart yet and cleaned. It has really loosened up and has a realy nice DA pull to it.
It happened to my son on DA firing. You could tell the primer had a very small indention compared to the fired rounds. These fired the second time. It did this about 5 times in about 80 rounds.

What is going on you think?

I can say dry firing the snub has improved my accuracy ten fold. Getting 4 out of 5 in the 10" target at 25'.:D
 
Tighten the strain screw in the front of the grip frame.

Lots of folks think that screw adjusts trigger pull.
It doesn't.

What it does is pre-load the flat mainspring for 100% reliable ignition.

rc
 
Whoa now, I don't mean to hijack this thread but...

I torqued down on that bad boy when I popped my side-plate off last and my firing pin strikes are so strong I have sheared the rims off of several Snap-Caps. Is this possibly the reason why? (Or maybe the Snap-Caps couldn't take several thousand dryfires? :confused:)

-Jake
 
Check also to see if the strain screw has been shortened. A lot of people...including some that went through Smith's armorer courses...used to do that to shave a couple pounds off the trigger pull. I run into that a lot.

If that's been done, tightening the screw won't help much. The screw should have a smaller diameter shank forward of the threaded portion, about 1/8th inch long.

The good news is that you can compensate for it to a large degree with a fired primer imposed between the spring and the end of the screw unless the whole shank had been filed off. A shade-tree fix, but it usually works. Or...Order another screw from Smith & Wesson. Be sure and specify round or square butt.
 
No such thing as a rim-fire model 10.

If you have a K-frame rimfire, it is a Model 17, 617, etc.

The strain screw needs to be tight in any K, L, or N-frame S&W to insure 100%+ reliable ignition.



BTW: Here is a box-stock mainspring & strain screw out of my Model 66 Sq butt.
Measures .580" OAL.

SW66StrainScrew.jpg

rc
 
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Depending on how old this revolver of your is, the main spring could have lost some of it's tension.

This happened to one of my 357mags and I ended up calling S&W and buying a replacement main spring for the hammer.

I was getting light strikes with no bang. Since I replaced the main spring it has been 100% reliable.

Just something to keep in mind, but try RC's way first, it doesn't cost anything and he is probably right.
 
It is a model 10-10, if that can tell the age. I'll look at it next week when my gunsmith freind comes back to town.
 
You don't need a gunsmith to tighten the strain screw.

All you need is a screwdriver that fits it.

And to remember this Rule.

Righty Tighty.

rc
 
You don't have to remove the grips or side plate.
The strain screw is visible if you look at the front of the frame where your little finger holds on.
 
I know I don't need him for just that screw. But what if it has been shortened? What if the springs are sprung? He told me to let him show me how to take the plate off.
 
The OP staed "I haven't had it taken apart yet and cleaned."

It may just be all gunked up under the side plate and just needs wiped out and lightly lubed. However, if you don't know to take a S&W side plate off and on I'd take it to someone who can do it for you.

I also agree it may be the strain screw has been loosened.
 
I'm really confused now. I read rc's measurement to be 0.58". I measured three screws on my three K frames. Two of them are 0.48" !!! But they shoot fine, I've had several thousand rounds through those guns with no problem. How could they be that much shorter than the screw rc has and still be reliable?

The third screw is 0.46". This one is on the problematic gun with the light strikes. I found the screw was 1/2 a turn out. I now have turned the screw fully in. I need to get to the range and test it out.
 
I know I don't need him for just that screw. But what if it has been shortened? What if the springs are sprung?
Click to expand...

Could be, but if you find that the screw is loose, that could well be the problem. Though I agree if the gun has a lot of rounds through it, the mainspring could be worn out. My 1959 K-22 required a new one a few years ago, and it dramatically cut down on the misfires. I think that part cost around $15.

Is this okay to do to a rim-fire Model 10?
Click to expand...

It really isn't okay to do on any S&W. In addition to misfires, which may not seem like a big deal on a plinking only gun, loosening the screw changes the geometry of the flat spring and it's relationship with the little stirrup thingie on the back side of the hammer which it engages. If you are unlucky enough to find the "sweet spot", the flat spring can increase the forces applied to that stirrup and snap it clean off.
 
Well, RC did mention that round butt and square butt guns use different screws. The 66 he measured the screw from is a square butt style.

The other thing I've found is where the mainsprings are "tweaked" to reduce the preload. In RC's picture the spring shown sure looks like a stock shape when you see it relaxed and out of the gun. So that's a good thing to compare your spring to. And there's no need to remove the spring from the gun and then fumble around getting the upper end fork back onto the cross pin. Simply slack off the tensioning spring until there's no load on it and look at the shape of your mainspring as it rests in the frame. Anything obviously different from the one in RC's picture is worth the effort to remove and carefully reform it to that same flat shape. But note that reforming a mainspring does damage it a little. If you reform your spring then plan on getting a replacement. The reformed spring won't snap on you but it won't provide the proper level of tension either. It'll be a little softer than if it had not been permanently deformed and then corrected.

Another thing you can try is to flush out the action and relube. If there's thick and gummy oil around the hammer it can slow down the fall of the hammer and produce light strikes. An example of this issue is waving your hand around in air vs waving it around underwater in a pool. The water or gummy oil acts like a viscous motion damper. Flushing the gun out with a solvent will do a lot towards removing this sort of gummy oil.

My suggestion for this on a revolver is to make up some Ed's Red mixture. It has the advantage that it's a highly effective soup of solvents for removing old oil and fouling as well as leaving behind a nice thin coating of protective oil to aid in lubricating and corrosion protection. To use it make up a small batch of the Ed's Red and with the grips removed use a little plastic squeeze bottle to suck up some solvent and then shoot it into the action through the mainspring opening in the frame and down through the openings of the cocked hammer, trigger slot, hand slot and cylinder stop openings. Work the action with the solvent in place. Do this flush and working of the action a few times then simply stand the gun up so the excess can drain out from the mainspring opening and dry out the solvent parts. Once the gun doesn't smell of solvent after a couple of hours you can wipe off the outer surfaces and replace the grips. The action will now have a nice crisp feel and sound when you dry fire it. At this point you can also check for any sort of friction point or grittiness in the hammer. Cock it back while feeling for any inconsistency or grabbiness in the draw. It should be silky smooth.
 
I am learning another new thing today. All of the screws I measured, came out of round butt guns.
 
CarlJ,

My money's on the strain screw as well but it could be a simple case of a few high primers in your ammo. Like others have said a good internal cleaning and relube won't hurt.
 
Thanks for the instructions guys. it looks like my buddy will be gone longer than we thought at the hospital fighting bladder cancer. So I'll go ahead and try some of this cleaning and go shoot again this weekend.
 
Hose it out with Rem-Oil spray, drip dry, and go shoot it.
Some oil & tightening the strain screw 1/2 turn will have fixed it I betcha!

rc
 
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