S&W K-frame question

[A-R]

OK, technical question for all your S&W revolver gurus ....

Just picked up a nice Model 66-1 .357 revolver - square butt, 4-inch barrel, pinned; recessed cylinder (apparently the true S&W fanatics like these older touches?)

Anyway, came with the original thin wood grips and some Pachmayr Grippers that leave the back of the grip frame exposed.

A while back another forum member graciously gave me a different set of Pachmayr Grippers from an old wheel gun he's fixing up. I like these grips better because they do cover the back of the grip frame and are more rounded off in the palm area (the others are more squared off). They are definitely intended for a square butt K-frame - says so right there on inside of the grips.

Problem is the grip screw hole lines up just perfectly with the mainspring - thus no way to insert the grip screw and tighten the grips onto the frame.

Is this normal? A few photos I've found on internet of other K-frames the mainspring seems more curved.

Is this mainspring "straighter" than normal, thus causing it to interfere with grip screw? Would this have been done as part of some trigger job years ago? The gun does have a very nice, light smooth trigger. Or were the mainsprings straighter on earlier K-frames, and later models had more curved springs (thus the reason Pachmayr put out two different square butt K-frame Grippers)?

Photos:

1. Shows the mainspring lined up directly with the screw hole on the preferred grips



2. shows the bare frame, main spring, and both sets of grips (notice how the grip screw hole is further toward the back on the grips that came with the gun - the ones that don't cover the back of the grip frame (left in photo). The grips I prefer to use are to right in photo.

[JCole]

I just checked my Model 19 with the same grips, and it appears that the mainspring in your picture is much too straight. I strongly suspect that someone cut down the strain screw to get a lighter trigger pull. Make sure yours is tight, and, if so, you'll probably need a new screw.

[longtooth]

Make sure it goes bang too. Mid 80s I was Reserve & Chaplain for a SO. One of the Deputies did his own trigger work & about 2 months after doing it went to qualify. No noise except for the laughing on the firing line & the screaming of the Range Officer.
He had been carrying a gun that would not fire for a couple of months.

[A-R]

the strain screw was a bit loose, but I tightened it and it moved the mainspring a bit but not enough to get the grip screw properly into place.

the screw itself doesn't show any signs of being shortened, but have nothing to compare it to. anyone know the exacty length that screw is supposed to be?

but there are some marks in the middle of the mainspring itself, where someone may have held it tightly with pliers or something and straightened it? does this make sense? would straightening the spring reduce pull weight or somehow improve trigger performance?

Guess I should've checked this one a bit closer when I picked it up. live and learn

gonna take it to range and make sure it's lighting off primers properly.

[JCole]

My strain screw is right at 15mm (about 9/16") long. I once got a Model 15 that had the mainspring bent in the middle, I don't really know what the point was. I replaced it with a Wolff spring before I ever shot it.

[A-R]

well I tried an "old trick" I read about on a S&W forum. Insert a used primer cap between the screw and spring and tighten down. Wa La! now the mainspring looks like the right curved shape and the grip screw fits.

I'll probably just go ahead and order new factory spring and screw for this gun to be on safe side.

Thanks for the advice, gentlemen. You certainly pointed me in the right direction. I was looking only at spring and didn't even think to examine the strain screw.