new s&w 686 mainspring problem

[bmortell]

hello I bought a new 686+ not too long ago, all factory ammo shot fine but cci primer handloads were light strikes 10 to 20% of the time. I read up on this problem and it said problems could be primer seating, altered/damaged mainspring or strain screw. After checking these i continued looking around and found that on the factory grip panels the little protruding plastic cylinder that the grip screw goes into pushes the mainspring forward when installing grips.

this pushes the mainspring forward roughly .050 a bit above where the strain screw is trying to keep the mainspring held back. as it was at about half cock the mainspring would lift off of this (grip screw housing) enough to fit paper shim inbetween. figuring this must not be intentional and causing my problem i took a sharp blade and carved a flat in the plastic cylinder until paper shim could fit between grip screw and spring with the hammer down.

if your having trouble picturing what i described taking one side of your grips off will make it obvious. was i right to modify the grips, i cant imagine that smith wanted half the mainspring power at rest holding the hammer down and the other half pushing on the grip screw plastic housing, which effectively lowers power during half of the hammer fall. i need to make more handloads to see if its fixed and ill update that shortly. thanks for reading, any imput is appreciated.

[wv109323]

CCI primers have a reputation as being hard. Another brand of primers may help your situation.

[bmortell]

I'm aware of the cci brand being harder than others, but I have a lot and that's whats available here. I loaded and fired 40 rounds with cci primers after modifying the grips and they all fired fine. but I'm still confused as to why a factory gun would have a plastic rod blocking and getting smashed by the mainspring?

[Ola]

... but I'm still confused as to why a factory gun would have a plastic rod blocking and getting smashed by the mainspring? Hah, everything is possible with factory guns. Most factories are not in the business of making high quality firearms. They are in the MONEY making business.

[hendere]

I'm having the same problem with mine but my grip screw doesn't come close to the spring. I get occasional light strikes with both Tula and CCI primers. No problems the same rounds in any of my other guns and I'm not interested in changing primer brands. The gun had about the most perfect out of the box trigger I've ever experienced, but started not going bang after about 700 or so rounds. The strain screw was about 3/4 of a turn out when I checked it. Screwing it in didn't help but the nice pull is gone. I installed a longer firing pin, that didn't help either. I picked up a replacement screw from Midway, it is a different type screw and a little longer. The trigger is even heavier now, and fewer misfires but still had 3 out of 50. I replaced the spring with a Wolff stock type today. Hopefully that does the trick. If not I guess I'll either send it back to S&W or sell it to someone willing to use Federal primers.

[Ola]

Take a look at the hammer. Is it moving freely in the frame? I have seen couple of S&W revolvers that needed couple of thin shims. With the shims the hammer moved to the center of the frame and was not dragging anymore. The strike was significantly stronger.

[Guesser]

I've read a lot of anecdotal reports on the "new" S&W reintroductions and their "plastic" problems. I was interested in a 66-8 until the dealer let me take the grips off. None of the "new" Smiffs will be coming home with me.