S&W Model 18 trigger fails to return forward.

[Radagast]

G'day all. My 1977 vintage Model 18 started giving light strikes at the range last night, every other round needed two double action hits to make it fire, single action shots didn't fire at all. Today I took the grips off and found the strain screw was backed out several turns. I tightened it down. As a result the hammer is no longer rebounding nor is the trigger returning forward. Very slight pressure pulling back on the hammer will bring it back to the rest position and the trigger then snaps forward.
Any advice as to what is causing it and what to do is welcome.

 

[rcmodel]

Needs an oil change, as it's well over 3,000 miles.

Hose it out with WD-40 while working the action, blow it out with compressed air, then hose it out again with Rem-Oil.
Then blow that out.

Whats left will be Goldie Locks just right.

rc

 

[Radagast]

Thanks. I'll give that a go. I assume I should not take off the side plate while doing this.

 

[rcmodel]

It would be better if you did, but if you are uncomfortable doing that, I wouldn't.

If you do take off the side plate you will need to unscrew the strain screw first to releive tensin on the hammer pin, so working the action won't work.
If you go that far, go all the way and strip it and clean everything.

rc

 

[Radagast]

I've a set of B-Square bits. If one of them is a good fit to the screws then I'll give it a shot. If not, nope. I'd rather not booger the screws.

 

[BBBBill]

If you've never pulled a revolver side plate, do not pry it off. Prying risks damage to the side plate and frame. Remove the screws, place your thumb over the side plate, and tap the grip frame on the side with a wooden hammer handle to vibrate the sideplate loose. A few taps will do it.

 

[Radagast]

Never done it before, but have watched it being done. That was the method I planned to use.

 

[chrisf8657]

To add in, if the cleaning doesn't work, it's time for a spring change - both Main and Rebound

 

[azgsmith]

New spring?

Just might be time for a new mainspring. Check with brownells or Wolff gunsprings for a kit. Its time anyway.

 

[Radagast]

After action report.
First thanks for the advice guys.
Bad news is I managed to peen the side plate. whacked away at the frame a few times, didn't come free. Repositioned my grip, forgot to put thumb over side plate and gave it another whack. Sideplate popped free and fell onto the cloth pad I was working over. Unfortunately Its now slightly lifted along the edge where the old fifth screw would be. Obviously it pivoted on that point as it fell off. *sigh*
I gave the action a good hosing out with Outers Crud Cutter, then gas, then Rem-Oil as per RC's instructions and put the thing back together correctly.
The toe on the bottom of the mainspring that locks into the cut out in the frame had slipped out. I repositioned this, put the side plate back on and tightened the strain screw down. Trigger return still failed maybe one out of three. So I backed off the strain screw half a turn and tried again. Perfect trigger and hammer action.

I Shot it tonight with CCI & Winchester ammo. 100% ignition and the DA trigger is much smoother - in fact I didn't think to shoot it in single action, I was having fun with the DA.

So two further questions:
a) As I had to back the strain screw off half a turn, should i assume the mainspring is on its way out?
b) The peening on the side plate. Is that an idiot mark I should leave along or would tapping it with a mallet to try and make it flush again be advisable?

 

[Old Fuff]

I presume the revolver was working before, and that the present issue is a new one.

1. If a previous owner shortened the mainspring strain screw or "reformed" (bent) the spring this could be causing problems if the screw isn't set "just so." Replacing the spring and/or screw would be the answer.

2 I don't wish you any bad luck, but you may have a cracked or broken hammer or trigger stud (the pin each part revolves on). If so the gun will have to go back to the factory. Rather then mess with the gun, I'd suggest you send it back rather then tinker with it yourself - unless you determine that it is the mainspring or screw. Sure it will cost, but nice model 18's are not easy (or inexpensive) to come by.

 

[BBBBill]

With all of the (justifiable and correct) warnings about the sideplate, I must also say that, while working part time in a gunshop back in the 70s/80s, I've seen many fresh out of the box from S&W with a slightly raised blemish at the "old fifth screw" location. So even the factory manages to screw the pooch occasionally.

 

[Radagast]

I purchased it in 2009, the trigger return was an issue then. It's the only Model 18 I'd seen for sale in Australia in 20 years, so I grabbed it. I had the local S&W service center check it over, whatever they did fixed the problem until now.
I'm not a gunsmith and generally I only see the main spring when I change grips, but the mainspring does seem to have an excessive bow to it. Unfortunately I traded off my other K frames last week, so I don't have another gun to compare it to.
The strain screw appears to be unmolested.

I think I'll take Old Fuff's advice and drop it in to the service center next time I get an opportunity.

 

[triggerman770]

if trigger return is an issue after what you did then you need to replace the rebound spring. while it's out I would clean and polish the frame where the rebound slide rides and the tunnel where the spring goues in.

 

[JimPGov]

triggerman770 IS RIGHT. SOUNDS LIKE IT WAS A CHEAP FAST (AND INCORRECT) ACTION JOB . THEY PROBABLY CUT A FEW COILS OFF THE REBOUND SPRING AND BACKED THE MAINSPRING SCREW OUT.

30YRS AGO I WENT TO A LOCAL BIG GUN STORE WHO HAD A FULL TIME GUNSMITH. $35 FOR THE ACTION JOB AND THATS ALL HE DID . OH AND HE GOBBED UP THE IN SIDE WITH GUNSLICK.

JP

 

[Old Fuff]

We can speculate what is causing the problem, but the 'smith at the Service Center won't have to. In the unlikely event that a hammer or trigger stud is cracked or broken it will likely be fixed for free. Can't beat the price.