39-2 Hammer Follow

hAkron

hAkron

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I picked up a 39-2 that looks a little rough. I took it out shooting today and I noticed it has a little bit of hammer follow. It's like this - If I thumb the hammer back to full cock, it stays on full cock. If the hammer is cocked by way of the slide, about 80% of the time it will stay back. If I test by racking the slide, then hitting the slide release (finger off of the trigger) it will come to rest on the decock notch. When I was actually firing it at the range today and I had the trigger depressed, when the hammer follow happened, I didn't check to see if the hammer came to rest fully forward on the firing pin, or if it landed on the halfcock notch. There were no double fires are anything like that. I detail stripped the frame and cleaned everything out really good (it needed it too!). The engagement surfaces don't look overly worn, nor do they look like anybody ruined them in an attempt to do a trigger job or anything like that. At least not that I can tell.

Given that, I think the issue might be in this sear spring that I've been reading about. As I understand it, I need to replace the spring, and ideally the pin that holds it in. I don't see it listed on the Numrich schematic...does anybody know where to source these parts, and also, does it sound like I'm on the right track?
 
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model 39

You may be on the right track suspecting the sear spring. Someone may have bent the spring, with the intention of lightening the SA pull. If you are able to take the gun apart, you might also check the sear notch on the hammer and the bevel on the sear to see that they are still sharp, and that there is no evidence of tampering/polishing etc. Use a magnifier if you have one and check the surfaces closely for wear, chips or tampering. Check the mainspring also, it may have been cut. Also, if you have a S&W armorerer in your area, they could check the gun for you.

Brownells has the new sear springs and pins in stock. Follow this link for more info:
s---w sear spring at Brownells
 
It's actually not a flat spring on my 39-2 sear, it's a coil spring/plunger deal held in by a pin. Numrich didn't show this on the schematic, but they did have a few parts that sounded like the right thing in the list. I ordered a sear spring (coil) and plunger. I didn't see the pin for sale, so ill need to reuse that. It doesn't look like anybody worked over the engagement surfaces, but I just looked with my eyes, I will check with magnification to see if the sear, hammer, and draw bar look good.
 
My apologies concerning the configuration of the sear spring. I thought the 39-2 was changed over to use the flat spring.
My book shows the OEM model 39 part numbers as: sear assy #6359, sear # 6113, sear spring #6116, s.s. plunger # 6114, and s.s. plunger pin 6115.
 
Thanks for the part numbers! I have the plunger and the coil spring on order, the pin I'll have to reuse for the time being. I also have a spring kit coming from Wolff which includes pretty much every spring in the gun other than the sear spring, so this should help tighten everything up. I'll update once I have the new parts installed.
 
It also could be the disconnector that is worn to the point it doesn't dependably disengage the drawbar from the sear. This, and the sear and hammer are the most likely issues.
 
That's a good point. The cross pin that stops the disconnector or from coming up too high in the frame is a little crooked. Perhaps that is effecting the position of the disconnector. When I have it all apart to respring it, I'll take a closer look at the disconnector.
 
I resprung the gun, including the sear spring and sear spring plunger and still there is periodic hammer follow. I'm almost wondering if gun is docking itself as though the safety/decocker was engaged. Does the ejector piece push down on the sear when you engage the decocker? Is that how it operates?
 
Actually, when you rotate the safety down, it pushes down on the sear release lever, which in turn, pushes the sear off of the cocking notch on the hammer. Did you have an opportunity to check the bevel on top of the sear, and the SA notch on the hammer with a magnifier? Just wondered if there was damage there, or evidence they had been stoned, etc. Did you determine the disconnector was OK? The old pinned ones can be a problem when the pin gets worn or bent.
 
The drawbar, sear, and hammer don't look altered. I will straighten out the cross piece on the disconnector to see if that helps.
 
Sorry ,, didn't read all the posts before I posted. you already replaced the main spring ,, and the problem sounds different than I had,, Sorry. Hope you get it figured out,,


A couple years ago I picked up a M39 and was having problems with it not firing and catching on the half cock notch when you pulled the trigger.
Someone on this forum ( I don't remember who) suggested I replace the main spring. A new spring was only a few bucks, and fixed the problem.

( Thanks again who ever suggested replacing the main spring ,,saved me lots of time and money )
 
Last edited:
It appears Midway USA has them in stock for $10.00. I'll throw one in on my next Midway USA order.
 
Midway, Numrich and Brownells are my usual sources.....and occasionally the factory will actually have a part in stock also, so don't forget to check S&W Customer Service if you're having trouble finding something. Did you say you had already replaced the mainspring?
 
Yes, I ordered a spring rebuild kit from Wolff which includes lots of springs. I stripped the gun down and changed out any spring included in the kit that had a match in the 39-2 (the kit is for every gen of 9mm). I also seperatly ordered a sear spring and plunger from Numrich.

Today I put the disconnector from my 439 (which is also the older style with the cross round cross piece) and sadly, same problem. I think the drawbar is the same between the 439 and the 39-2...maybe the hammer as well. Perhaps I'll try swapping a few things around to see which piece the problem follows. I bought both the 39-2 and the 439 as project guns so while I don't want to put a ton of money into them, I do want to tinker around with getting them fixed up.
 
How are you testing? Are you locking the slide back, then releasing it onto an empty chamber?
If so, try holding the trigger fully back when you drop the slide, when the slide is fully down, release the trigger slowly.......do you hear an audible click when the disc/sear reset? Does the hammer stay back when you hold the trigger back and drop the slide?
 
armorer951, on my RCBS trigger pull scale, my 39-2 SA trigger breaks at around 3.5lbs. Using the same technique on my other 39-2 (one with no hammer follow) the trigger breaks at about about 4.25lbs. Both of these are a rough average of about 5 pulls.

Interestingly, if I test by just dropping the slide on an empty chamber the hammer will follow about 1 in ever 3-5 tests. If I keep the trigger pulled back I was unable to get it to fail in 10 tests. My 'control group' non-broken 39-2 doesn't show hammer follow during either type of test.

I would say at this point that I'm following your logic of either a warn engagement surface somewhere on the sear, hammer, or draw bar, or an over eager trigger job on those same parts.

I do remember hammer follow even on test where the trigger was held back prior to replacing all of the springs, so perhaps I have resolved the practical aspects of the issue, at least where it might show up in normal use. I'll have to go to the range tomorrow to see how it works in live fire. You have been a great help so far armorer951 thanks!!!!
 
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