Firing Pin Stop Slid Down During Cycling

[Rooster1960]

I was hoping someone could tell me what would allow the firing pin stop to slide down and catch the hammer as the slide returned to the forward position? Happened today on a Series 80 Commander. I removed the firing pin assembly, extractor, and firing pin plunger and don't see anything that seems wrong??? Please Help

[Ariz Commander]

I'm no gunsmith but from a common sense point of view I would have to guess a weak firing pin spring. You may also want to check the hole the firing pin goes thru to contact the rounds primer. If it contains any fouling or dirt this may cause the pin to stick, The rear of the pin extends thru the hole in the pin stop, the only way for it to drop is if the firing pin is pushed all the way forward. If it is dirt in the firing pin hole this could be dangerous as the pin could be exposed enough to strike the primer on the next loaded round causing it to discharge prematurely or unexpectedly.

[stans]

Weak firing pin spring or really sloppy fit of the firing pin stop or a firing pin that is shorter than spec.

[Rooster1960]

Thanks for the help. Just ordered a firing pin, stop and spring from Wilson Combat...see if that takes care of it. When I took the pin out...it wasn't really dirty and had no way to check the spring rate but the fit of the firing pin stop WAS sloppy. I'll post the outcome when the parts arrive. Thanks again!!

[Unclenick]

Aside from the source of the problem (springs, fit, etc.), it is really common to use a punch to upset the edges of the firing pin stop so you can stone them to achieve a friction fit.

http://img121.imagevenue.com/loc80/th_9af_Firing_Pin_Stop_4B.jpg

The upsets are exagerated and not yet stoned here, but you get the idea.

Nick

[stans]

I've done the punch thing and it usually works, but not likely to work well with today's MIM parts. MIM doesn't flow, flex, or bend, it breaks. Forged and bar stock machined parts do allow the metal to flex and flow just a little.

[1911Tuner]

The firing pin springs in Series 80 Colts were and are notorious for that little trick. The reason? They're shorter than standard springs. Get a standard-length spring and it should solve your problem. if it doesn't, the Wilson MIGHT...depending on a few dimensions. The fitted EGW will do the trick for sure.

[Unclenick]

Stans,

Is Colt now metal injection molding this part? The last Series ‘80 I did that was all-Colt parts didn't have this problem, but that was awhile ago. If I understand the MIM process correctly, the metal has to be cooled slowly after the sintering stage to keep shrinkage uniform and avoid distorting final dimensions. I don't know what happens if you try to heat treat such a part afterward? Since it has to spend a long time in the oven cooling down, they probably skip heat treating by picking a relatively hard alloy. No grain orientation beyond the size of the original metal particles. There is a metallurgist on the Firing Line forum. I'll ask if he knows?

An alternative would be to try dimpling the slide just above and/or below the firing pin tunnel to see if that achieves enough grab? I think the slide is a little big for a MIM part, but I’m not current on the process. It used to be a rule of thumb that about 7 ounces (200 gm) was the upper limit for it.

Nick

[Rooster1960]

My parts from Wilson arrived today...Firing pin, firing pin stop, and firing pin spring. Tuner1911...I couldn't believe the difference in length between the spring I took out and what Wilson sent me!!! The firing pin stop said it may require fitting and I expected the fitting to be on the sides where it slides into the slide. My commander may be oversize because it slid in the groove fine. The adjustment that was required was so the sear would clear the firing pin stop during reassembly. Went out to shoot and it seems this problem is cured. I think the spring alone would have fixed the problem though. Now...if I can just get it to feed the last round in the magazine consistently. Thanks for Everyone's suggestions!

[1911Tuner]

Howdy Rooster,

The longer spring will probably solve the problem. Just remember that it's unidirectional and goes on the pin one way. It's sized to be a press-fit on one end. If it slips onto the pin easily, turn it around. Removal requires a
little pull and turn to prevent stretching the spring. It may be tight enough that it also requires push and turn...but most just press on.

Wilson's "oversized" stops aren't really oversized in the true sense. They're
machined to maximum tolerances, and will only require fitting if the slot in the slide is at or near minimum...and only a little in those rare cases.