View Full Version : firing pin stop on 1991A1

bill boyd
May 24, 1999, 10:18 PM
I was shooting my 1991A1 Officers mdel tonight when the firing pin stop came loose and jammed the slide open. Islid in back into place and it came loose after a after a few more rounds. What would cause this? Has the firing pin spring become weak?

George Stringer
May 24, 1999, 10:33 PM
Bill, more than likely. A heavy duty firing pin spring may put a stop to it. You can also have it drilled and tapped for a set screw and there are oversize stops that are fitted very tightly. The cheapest fix is of course the spring. George

bill boyd
May 25, 1999, 05:20 AM
Thank you. Do the springs come standard weight increments? What would you suggest or should I buy two or hree different weights and experiment?

May 25, 1999, 06:22 AM
Just a thought, Bill: You might also check to make sure the firing pin channel and firing pin block channel are clean and free from obstructions.

By the way--My grandfather's name was Bill Boyd. :D

George Stringer
May 25, 1999, 07:02 AM
Bill, you might contact Wolff at www.gunsprings.com about weight increments. All I have ever seen are standard and heavy duty. George

Rosco Benson
May 25, 1999, 07:40 AM
You can peen the edges of the firing pin stop slightly, to cause it to fit tighter.


James K
May 30, 1999, 09:22 AM
Just to show a little of what is involved, I'll repeat what I said on another thread. What applies to the Model 1911A1 also applies to the Colt Model 1991.

I have done some research, and like almost everything else about guns, the situation is a little more complicated than it seems.
When the M1911/A1 is fired, the hammer drops on the firing pin, driving it forward. It is prevented by the cartridge from going far enough forward at that time to free the firing pin stop.

But that is not the end of the story. When the cartridge fires and the bullet starts to move, the slide moves back in a hurry. It moves so fast that it does not push the hammer back like we usually think. It hits the hammer a hard blow, and kicks it downward, where it bounces off the grip safety.

At this point, the cartridge has been partially extracted, and is forward against the hook of the extractor. The firing pin is still forward and is being pushed farther forward in relation to the gun by its own inertia (especially if the firing pin spring is weak), the hammer is not touching the slide or the firing pin stop, and the recoil has moved the gun.

The firing pin stop is free to move, but it really is trying to stay in one place while the whole gun moves in recoil. (Good Old Newton strikes again!) The result is that it jumps out of its position in the slide. This will cause the gun to jam and the stop usually falls out while attempting to clear the jam.

You can see that the whole thing depends on a lot of involved timing, which is why dropping the firing pin stop doesn't happen often.

A heavier spring may solve the problem, but a better way would be an oversize firing pin stop. Brownell sells these for about $13.00. They allow the stop to be a drive fit and eliminate the problem without any other parts.


P.S. For those who doubt that the hammer is knocked back hard by the slide, look at the underside of the firing pin tunnel in the slide. If the gun has been fired much, there is a dent, caused by the hammer bouncing off the grip safety and hitting the slide as the slide recoils.


bill boyd
June 1, 1999, 10:26 PM
Thank you for the suggestions. I guess I'll order the oversize firingpin stop and a heavier spring wile I'm at it