986 light primer strikes

[Skookumchuck]

Hi all, big S&W fan from Canada here! In february I treated myself to a brand new 986. Love the gun, love the accuracy, love the feel. It's my first L-frame. Not loving the reliability. I loaded up 22 moon clips with American Eagle 115 grain for some steel challenge practice on Tuesday night and had 8 light primer strikes. I could figure out how to load pictures if that would help but the dimple in very noticeably lighter, and my computer literacy is just slightly above nincompoop. Before I send it for warranty I thought I would let the combined knowledge of this forum chime in.
Skook

 

[armorer951]

Welcome to the forum.....

Presuming you have an unaltered factory revolver at this point, I would check for the obvious reliability culprits, like the tightness and integrity of the strain screw, and shooting debris under the extractor. I would also try a variety of different ammunition brands, if you can lay your hands on some, to make sure that the ammo is not responsible.

Ruling out any other obvious flaws, you may want to consider checking the OAL of the factory firing pin. In my experience, some factory pins are quite short, below .490". Longer, aftermarket pins are available from vendors like Power Custom, and Apex, and may actually help with your reliability issues.

Sending the gun in is always an option, but considering the status of Customer Service at the moment, that would be a last resort, IMO. Hope you are able to sort out the problem.

 

[SW Gun Guy]

I agree, trying some different ammo is the first idea. If you still get light strikes, maybe mark the chambers that fail with a Sharpie and see if the same chamber(s) are the culprits every time. Not sure what that would prove, but somebody here will have an idea. Of course all of this is after a complete cleaning and very light oiling. Keep us posted.

 

[twodog max]

First and easiest thing to check IMO is if the strain screw is screwed all the way in. Remove the grips and if the screw is not all the way in then as I understand it it has backed out. I have had this recurring problem with a few of my S&W revolvers. Particularly L frames for whatever reason. Only takes a few minutes to check and may immediately fix the situation. If not the problem then move on to other suggestions.

 

[dmy]

After checking the strain screw, I suggest trying thicker moon clips. A thicker moon clip causes the cartridge rim to be slightly closer to the firing pin.

 

[__steve__]

I had this problem start happening randomly with fairly new revolver. Turned out to be this grey, gritty crud built up within the firing pin/spring assembly.

Worst part about this issue is if a squib also just happens to occur, and it is carelessly assumed to be another primer strike light and go on to next round. I actually had both occur at same day and I am very thankful I didn't assume it was a light strike (like the 5th one that day). That is because a 1/2" diameter 350gr FMJ FP bullet became lodged far enough into the forcing cone to cycle to the next round. I actually thought it was a light strike again until I opened the cylinder and powder fell out. As I write this I am just now realizing how bad it could have gone.

 

[Notaglock]

Hi all, big S&W fan from Canada here! In february I treated myself to a brand new 986. Love the gun, love the accuracy, love the feel. It's my first L-frame. Not loving the reliability. I loaded up 22 moon clips with American Eagle 115 grain for some steel challenge practice on Tuesday night and had 8 light primer strikes. I could figure out how to load pictures if that would help but the dimple in very noticeably lighter, and my computer literacy is just slightly above nincompoop. Before I send it for warranty I thought I would let the combined knowledge of this forum chime in.
Skook

Is it a Performance Center model? My 627 Pro came from the factory with a reduced power "bossed" mainspring and a loose strain screw. I put an Apex firing pin kit in it and with the strain screw tight, it's been running 100% with everything I feed it.

 

[gerhard1]

American Eagle is Federal, hence fairly soft primers already. My 986 had issues with hard primer brands (Winchester, Fiocchi) but was pretty reliable with softer brands such as Remington or Federal. Check the strain screw as others have said, and look into getting a longer firing pin.

 

[Skookumchuck]

It's a Pro series. The strain screw was backed out about a full turn. Correct me if I'm wrong but wouldn't tension of the screw supply uniform strikes regardless of whether it was tight or loose? All my other Smiths are older, firing pin on the hammer style. This firing pin doesn't look like it comes out easily? I blasted G96 into it from both sides but it appeared to move freely before lubing. I'll take it to the range this afternoon and report back.

 

[__steve__]

This is what was making mine stick:

I was actually able to feel the pin on occasion bind up by manually pressing it while hammer open
In my case the mod 500 was 3 years old when I purchased it "new" from the dealership, just 2 months prior to failing.

I thoroughly cleaned the pin, spring and bore, I put just enough corrosion inhibitor to coat the surfaces, then I carefully removed any extra with lint free swab. About 500 shots now with zero defects.

This was the cause of my light strikes. The reason was mild corrosion and too much lube.

It also wasn't too easy disassembling the gun. Without quality tools and experience can easily lose or break parts in process if never attempted

 

[stu1ritter]

It's a Pro series. The strain screw was backed out about a full turn. Correct me if I'm wrong but wouldn't tension of the screw supply uniform strikes regardless of whether it was tight or loose? All my other Smiths are older, firing pin on the hammer style. This firing pin doesn't look like it comes out easily? I blasted G96 into it from both sides but it appeared to move freely before lubing. I'll take it to the range this afternoon and report back.

The strain screw must be tight. Backed out one turn will cause light strikes. From the S&W Armorers Manual "The strain screw is always to be fully bottomed in the frame. Mainspring weight adjustments are made by filing the screw length."

Stu

 

[Notaglock]

It's a Pro series. The strain screw was backed out about a full turn. Correct me if I'm wrong but wouldn't tension of the screw supply uniform strikes regardless of whether it was tight or loose? All my other Smiths are older, firing pin on the hammer style. This firing pin doesn't look like it comes out easily? I blasted G96 into it from both sides but it appeared to move freely before lubing. I'll take it to the range this afternoon and report back.

The firing pin isn't too difficult to replace but you do have to take off the side plate to get to the retainer pin. No need to completely disassemble it to replace the firing pin, just lift out the hammer block, loosen the strain screw all the way and cock the hammer.

 

[Skookumchuck]

Didn't get to the range yesterday, hoping to make it today. Very specific question hopefully with pics. Should all primer dimples be uniform?

 

[VikingDude]

That imgur link does not work.

But if you still have problems with the strain screw screwed all the way in, you should do what armorer951 suggested and check the length of the firing pin, while you have the firing pin out you should clean the firing pin channel also. You could try with an aftermarket firing pin that is longer, I usually go for the one from Cylinder & Slide, but I have also experienced that the strain screw might be a tad to short and need replacing with one that is a little bit longer.

 

[Skookumchuck]

Made it to the range today and shot 17 moon clips with no light strikes. I didn't think it would be that easy to solve but maybe it was. Thanks for all the advise.
PS How do I post pictures?

 

[geekeye]

blue locktite on the strain screw will stop it from backing out again. if you need to take the mainspring out and the screw doesn't want to come loose for you after using locktite, just hit it with a bbq lighter for a few seconds to melt it.


you can post a pic by using the attachments button (paperclip icon), then embed the url of the attachment into your post (picture icon).

 

[twodog max]

Glad you got it figured out easily

 

[Skookumchuck]

I'll try one more time to post a pic and delete if I fail.

 

[Skookumchuck]

Now I just have to figure out how to make them a little smaller.
While I have the attention of some very knowledgeable revolver enthusiasts I will ask shouldn't all the dimples be uniform regardless of whether the strain screw is loose or tight? In the interest of confirming this was the cause of the problem I will back the screw out again to where it was and see if the same thing happens.

 

[Notaglock]

Now I just have to figure out how to make them a little smaller.
While I have the attention of some very knowledgeable revolver enthusiasts I will ask shouldn't all the dimples be uniform regardless of whether the strain screw is loose or tight? In the interest of confirming this was the cause of the problem I will back the screw out again to where it was and see if the same thing happens.

The main reason the ones that went boom have larger firing pin impressions is because the pressure inside the fired cases flattened the primers against the recoil shield and molded them around the protruding firing pin. If you back out the strain screw you're going to get light strikes again.