View Full Version : 22 unit

August 3, 1999, 01:33 PM
Have a colt 22 conversion unit.It was probably made in the 70 or 80"s.Model # on the box is 3150.Having a problem,missfires almost every other round.It will fire the missfired round on the second hit.I checked the firing pin and noticed that the tip is sort of squared off and not round like the other firing pins in my other colts.Is this normal for the pins in the conversion unit ?


James K
August 3, 1999, 02:21 PM
By squared off, do you mean that the end is a flattened circle or that the cross section is square/rectangular? Also, is the kit for the Model 1911 type pistol or the AR-15? With a little more info, I may be able to help more.


August 3, 1999, 06:55 PM
the conversion unit is for the 1911 series 70 or older type.The fireing pin is not round.IT is not a clean flat either its to close to call,thats why i wanted to know if the fireing pin tip is supposed to be round.


George Stringer
August 3, 1999, 11:05 PM
Harold, a rimfire firing pin should be flat and appear to be retangular when looking at it from the front. Clean firing pin recess and check the hole for dings or burrs. I have had success in the past with stretching a firing pin by a couple of thousandths by laying the forward part flat on an anvil and giving the body of that forward part (the smallest diameter, part that strikes the case rim) a few raps with a ball peen hammer. Sometimes a couple of thousandths is all it takes. Check your firing pin protrusion. It should be around .040". George

James K
August 4, 1999, 12:57 AM
Hi Harold, hi George,

The Colt conversion unit firing pin is round as seen from the front. It is flat, with the edges rounded somewhat but it is neither dome shaped nor rectangular.

My thought is whether things work OK with the .45 slide in place, and whether anything has been done to the hammer or spring.

Another thought is the ammo. Some of the hot new .22s have harder cases than the older ammo the conversion unit was made for.

If none of the above apply, and the unit is clean, try George's idea of stretching the firing pin slightly. It does work.


August 12, 1999, 08:30 PM
I looked at my Colt 22 conversion. The firing pin looks a lot like a 45 pin except it looks like a flat has been filed on the tip. Is the floating chamber very clean? Mine has misfires when it gets the slightest bit dirty. Bill

August 13, 1999, 11:18 PM
My Colt ACE runs fine with a dirty floating chamber. I shoot allot of the Wal- Mart Federal plated stuff through it and I only have problems with it when it totally clogs up.


August 14, 1999, 12:27 AM
Somebody correct me if I'm wrong, but doesn't the Colt factory conversion unit come with a different mainspring? I've seen ads for the current unit Colt sells and it lists a whole new mainspring housing as part of the package. This could be the problem with Harolds gun, wrong mainspring.

August 14, 1999, 06:08 AM
the mainspring that comes with the 22 conv unit is colts new alloy 22 conv unit made for the series 80 pistols,mine is the all steel conv unit made in the 70 and 80's


August 19, 1999, 01:02 AM
Sorry to butt in, but do any of you gentlemen know someone that has a Mitchell .22 conversion kit they might be willing to part with?

August 19, 1999, 07:20 AM
Its working now.Minor problem ,the fireing pin was peened on the end.Replaced and now works fine.