Using Strain Screw for DA pull?

[Wheel-er]

I'm reading conflicting info on lightening DA trigger pull on m64-5.

Some say un-screw the Strain Screw to lighten the DA pull to desired pull. You'll know you've gone too far if the hammer can not fire a round.

Others say Strain Screw MUST be seated. Or it affects other part's moving relationships and they won't work as well together. So pay gunsmith to alter or change main spring.

A third group says the Strain Screw can be loosened up to a full turn, maybe turn and a half, w/ no problems. (but little results?)

Which is correct?

 

[handgunner356]

Well people have messed with strain screws since the dawn of time so it's nothing new. I've had guns that the screws were loctited, screws ground off, springs bent or ground thinner with the usual results, the gun ends up not firing. Often refered to as a "cheap trigger job" backing out the strain screw to the point of not firing then back in a half-turn doesn't hurt a range gun, although when the screw isn't seated it will back out on it's own if not loctited in place.

 

[dfariswheel]

There's a big difference between range toys or target guns, and self defense guns.

If you wind up with a tension screw that backs out or is improperly set and you have mis-fires in a range toy... no great loss.

If you have the same problem in a defense gun.... you die.

In general, the strain screw should be tightened down TIGHT and kept that way.
Trigger jobs (actually an action job) in revolvers is best done by installing a spring kit and/or having the action professionally smoothed up.

Today, a "good trigger" isn't necessarily a light trigger, its a SMOOTH trigger action.
Many of todays speed shooters actually install stronger springs.
Lighter springs not only can cause ignition problems, they actually slow you down due to a slower to reset action and a slower hammer fall.

If you want a lighter trigger action backing out the tension screw really isn't the way to get it.
In addition to ignition problems, the backed out screw can cause mainspring "knuckling" problems and make the action worse.

If you want an action job and don't want to pay a pro to do it, invest about $25.00 in the Jerry Kuhnhausen shop manual.
This was written as a training aid fro new pistolsmiths, and covers everything you could want to know about the S&W revolver, including the right way to do a trigger job:

HERITAGE GUN BOOKS : THE S&W REVOLVER - A SHOP MANUAL - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools

Using the manual and a screwdriver set from Brownell's, you can disassemble and install a spring kit yourself.

http://www.brownells.com/.aspx/pid=413/Product/S_W_SCREWDRIVER

 

[PhysicsGuy]

You can also file the strain screw to the desired tension when seated. But I usually suggest to have the screw fully seated, if it comes loose from where it is set, then you will have a temporarily disabled gun (which at the range isnt a big problem).

Easiest way I found to adjust your DA pull is to change the mainspring and trigger return spring.