After firing about 500 .357s and 1000 .38s through my new 686plus pro series I started to have misfires. Well turns out my strain screw got loose. So, Obviously I need to retighten and loc-tite it. But, how tight is it suppose to be? I tightened it pretty tight and stopped the misfires but now my trigger pull seems heavy. What's the best way to go about this?

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S&W 686-6 Plus Pro Series

the strain or mainspring screw should always be as tight as you can get it, never loosen to get lighter pull. you will need new springs for that, also never loctite the screw.

Use 222 Purple Loctite. Clean the strain screw and frame with acetone first. Many, as witnessed above, think it's a sin to not have the strain screw fully tightened but think shortening the strain screw is acceptable. Seems to me the result is the same.

On stainless guns I replace the strain screw with an 8-32 socket set screw. The alloy/heat treat of the stainless strain screws seems to be a bad choice. The carbon steel strain screws of the blued guns do much better and don't get mushroomed tips and loosen like the stainless strain screws.

Look at the mainspring. Does it have a rib running down it's length? If it does your gun came with a Wolff reduced power mainspring. Some models come with the Wolff spring stock, I don't remenber if the 686 Pro's do. If it doesn't have a rib, get a reduced power Wolff mainspring. Adjust the strain screw for reliable ignition and loctite it. Preferably the 8-32 socket set screw as the stock stainless strain screws just keep deforming.

Loctite the yoke screw too so you're not one of the guys with your yoke and cylinder laying on the ground when you open the cylinder.

The strain screw should NEVER be kept in any position except fully tight! If you want to reduce the strain on the main spring, then the screw may be slightly shortened and reshaped as originally. I suggest doing this on a replacement screw and not the original, should you go too far or want to return it to Factory specs; they are certainly cheap enough!'

As far as Locktite goes, I personally do not use it on firearms - no exceptions. I know there are plenty on this and other Forums that tell people to use the stuff, and I own at least three different grades (or colors) for different amounts of holding power, but I still do not think it has any business to be used on guns. I have NEVER had a strain screw loosen up (assuming it was properly tightened in the first place) during the normal course of firing a revolver. In fact, the only part of a modern S&W revolver that does seem to work loose once in a while is the ejector rod, which is simply cleaned and properly re tightened when and if it does occur. Locktite sometimes causes more problems than it solves. I've had many calls from friends that can not get their screws out when they want to get them out. Sometimes the Locktite migrates to other parts that you don't want it to get into. I just think that it is a drastic measure for a simple fix. Just my opinion of course........

Chief38