DA fail to fire, SA fire ok

[mjrodney]

Out shooting a friends revolver this afternoon.

Three rounds out of a cylinder of eight .357mags failed to fire, shooting double action.

I put the 3 back into the cylinder and all 3 failed to fire again when shooting double action.

Tried it a 3rd time, but now in single action mode and all 3 fired normally.

Huh?

Coincidence? :confused:

[KurtC]

On single action, the hammer is cocked all the way backed, using the full force of the mainspring. On double action, the hammer does not come all the way back (or it would stay on the single action cocking notch).

You need a stronger mainspring, or tighten the tension screw if it is a S&W.

[gb_in_ga]

I was going to give a meaningful reply, but KurtC said just about exactly what I was going to say.

SWMBO's revolver (S&W 15-2) did the same sort of thing when she first got it, used. It turned out that the strain screw wasn't tightened properly. Tightened the screw, and voila! No More Problem.

[mjrodney]

Good answers. Thanks.

I suspected that a double action hammer fall was shorter than the single action fall, but I wasn't entirely sure if it would be enough to cause this problem.

Apparently, it can be.

[Tom2]

YOu did not say if the primers were dented when they did not fire. If it is a light strike from a weak spring or something, that should be visible on the primer. Check that if it happens again. If the primers looked as dented as ones that fired, perhaps it is bad ammo or reloads? On handloads, if the primer is not seated fully, just slightly below flush or flush at least, the anvil in the primer will not be seated against the case and may soak up some of the hammer blow. Or old primers in handloads may cause problems I suppose. Or ammo exposed to bad temp extremes or oil.