[ColtCowboyIII]

Hey guys,

I had my Trooper MK III out at the range today and everything was going great until my friend wanted to try rapid fire. When we pulled the trigger quickly (in DA), the cylinder cycled and the hammer fell, but the bullet did not fire. We kept it on target for 30-45 seconds just in case it was still hot, and then opened the cylinder. The primer had a very light dent, but not enough to ignite the charge.

The gun fires flawlessly in SA and had been working perfectly in DA when we were pulling the trigger slowly for precision shooting. Once we pulled the DA trigger quickly, we started noticing the problem. We did not pull the trigger multiple times in rapid succession. Only pulled the trigger back rapidly to fire one round and immediately had this issue occur. We then tried everything again under the same circumstances (SA, DA slow, DA rapid) with the same results for each.

So what's going on? How do I remedy this?

Thanks in advance for your help.

CC3

 

[ColtStar]

Assuming the transfer bar & firing pin is up to standard, and the ammunition is good, You may need a new main-spring, ie, hammer spring.
It's possible that your spring is simply weak from usage, or perhaps someone clipped a couple coils off the hammer spring.

New springs are not very expensive, and can be had from at least a half dozen sources.
I generally buy all My gun springs from (link >>>) Springs for COLT Revolvers (scroll down the page for Mark III)
Notice there are several weights available, from 11.5 lb to factory original weight of 16.5 lb.
Hope this helps!

 

[Lawman67]

The original springs are around 15 lbs, i have had no problem with wolff 13 lb mainsprings and their replacement rebound spring. usually you will run into problems with other replacement springs and if you try to lighten the pull by clipping coils

 

[dfariswheel]

In addition, inspect the firing pin. It seldom fouls or give problems, but check to see if it moves freely in and out, and that the tip isn't broken or chipped. (NOTE: DO NOT attempt to remove it. Removal or replacement is a Colt factory ONLY job due to special tooling required. Try it with a hammer and punch and you seriously damage the frame).

Next, try cleaning out the action. You can spray a gun scrubber type cleaner up inside with with the grips off, dry thoroughly, then spray in a good lubricant. I don't like the really thin lubes like Rem-Oil for this.

Inspect the transfer bar to insure it's not bent or broken, and that it has slight spring pressure pushing it to the rear when the hammer is cocked.
It's unlikely, but a bar that's worn thin will cause mis-fires especially in double action.

Inspect the cylinder assembly for end shake.
This is excess back and forth movement of the closed cylinder. This can be checked by pushing the cylinder to the rear and holding it there while you use an automotive feeler gage to gage the gap between the cylinder and rear of the barrel.
Push the cylinder forward and hold it there while you gage the gap again.
Subtract the one measurement from the other and that's how much end shake is present.
Anything over 0.003" requires factory repair. NOTE that NO local gunsmith can do an end shake repair to a Colt revolver. Again, this is a factory ONLY repair requiring a special machine to do it.

Check again with different ammo. It's possible it's an ammo issue.

 

[JudgeColt]

I have seen cases where the double action parts are worn or out of specification to where the hammer is not drawn far enough to the rear to gain full power. Check that as well.