Colt Service Model Ace 22 unit

[jim c 351]

Last Saturday I bought a Colt Service Model Ace 22 Unit. The rear end of the slide has 4 numbers stamped,---17 above the firing pin hole and 05 below the firing pin hole.
My question concerns the firing pin.
The max dia of the firing pin, near the rear, has a hole without a pin. Since the slide had a groove going down from the firing pin hole, I figured the pin was important to keep the firing pin from hitting the barrel.
As a stop gap measure, to prevent barrel damage, I fitted a roll pin into this hole . I'm not optimistic a this pin lasting for long
Whats the story on these firing pin stop pins?? Is it common for them to fall out?? Are they press fit or soldered in place?? Are new firing pins available?? Where are they found and how expensive are they?? Any dealer specialize in service ace parts??

I did not get a magazine or slide stop with the unit, but I had 2 mags on hand that seem to work just fine. They are 2 tone and marked Colt Ace (in triangle) 22 LR. The loading slot runs parallel with the body. I believe these are the wrong mags for the unit , but they work OK, and that with the Military issue slide stop.
All thoughts and opinions welcome.
Thanks ,
Jim C 351

[Johnny P]

Could you post a picture of that? I have one of the late Parko-Lubrite Service Model Ace uppers, and don't remember anything like that.

[dave]

I have a Colt unit, no Ace name on it, matbe later model. Only pin I can see holds rear target sight in place. I did not pull slide back to look under the slide. Split pins are very hard, may not wear at all. Did you try firing with that pin in place? seems it would restrict pin travel and not hit cart. rim.

[Johnny P]

The groove in the firing pin stop plate is to allow disassembly. The firing pin of the Service Model Ace is longer than the standard Model 1911 firing pin, and the clearance is needed to slide the firing pin stop plate down.

The firing pin on the bottom is the Model 1911.

[jim c 351]

pictures of Colt Service Model Ace

Here's the pictures you requested.
Jim C 351

[Johnny P]

This is what your firing pin originally looked like. The early firing pins had a different profile to the tip. The early firing pin was more wedge shaped, and the groove in the slide and the guide on the firing pin kept the firing pin from rotating, keeping the wedge shape vertical. This was eliminated on the later SMA pistols, with the tip of the firing pin being round.

[jim c 351]

Johnny,
Thanks for the info. Here's some more questions.
Is it common for the guide pin to become lost? How is it held in place??
It appears to me that in addition to keeping the firing pin from rotating , it also prevent the firing pin from hitting the barrel. Is this correct.
Are the later firing pins interchangeable with the early FP?? What prevents the later pin from striking the barrel??
Are either the early or late FP available ?? Where?

I think my Magazine is for an ACE, not a Service Ace. Is this correct??
Thanks again.
Jim C 351

[Johnny P]

The shoulder (see arrow) prevents the firing pin from going in too far. As mentioned, the guide is to prevent the firing pin from rotating. The later style firing pin without the guide can be used in the early SMA pistols since the tip of the firing pin is round. Have no idea about availability.

From your description of the magazine with ACE in a triangle (actually a diamond) it is for the Colt Ace. SERVICE MODEL ACE will be spelled out on the SMA magazine.

[jim c 351]

Johnny,
Thanks for the great information.
Do you have any idea what year SM1705 was made??
And at what point did Colt go to the improved firing Pin?/
Thanks again.
Jim C

[Johnny P]

SM 1705 was made in 1941. Just a guess on the firing pin, but production ended in 1942 and resumed in 1945, and I have a feeling the firing pin was changed when production resumed.