[Tom B]

I am getting lite strikes about every 20rds in DA with my M10. Its a 1973 vintage with hammer mounted FP. I installed a new Wolff mainspring in standard weight but still have problem. Any ideas?

[dfariswheel]

If you bought the gun used, check the strain screw. Somebody may have shortened it.

I'd replace the mainspring with a S&W genuine factory part, and the strain screw too, just in case.

The internals may benefit from a good cleaning, but I'd suspect the spring and screw first.

As a possibility, you might check the firing pin for proper length.

[Standing Wolf]

If dfariswheel's good advice doesn't do the trick, try other brands of ammunition: some primers are harder to ignite than others.

Personally, I use Wolff springs in lots of guns, and have been using them for years without trouble—but there should never be anything wrong with a new Smith & Wesson spring, either.

[Old Fuff]

Your revolver may have excessive cylinder "end shake" a.k.a. "end play," which is back-and-forth movement as opposed to rotational movement. When this happens the cylinder can move forward away from the firing pin, resulting in a light strike. This condition is easy too fix, but requires a knowledgeable owner or gunsmith. If you detect the condition and can't find anyone in your area to fix it, return it to the factory.

[Tom B]

Thanks for the replys. The revolver doesn't have very much end shake or cyl play at all. The strain screw is tightened all the way. I will check its length against my M66 screw.

[JoeHatley]

Tom,

It sounds like your M10 is right on the edge with it's light strikes.

A used primer cup, placed over the end of the strain screw, will effectivly "lengthen" the screw a bit. Might be just enough.

Good Luck...

Joe

[Mike Irwin]

Are you shooting handloads or factory ammo?

If you're shooting handloads, it might not be the gun, but the occasional improperly seated primer.

The "light" strike finishes seating the primer, the subsequent strike fires the round.