View Full Version : Top reasons for no half cock on a single action?

May 4, 2012, 03:50 PM
What would be the top reason(s) for a single action revolver to miss the half cock position? When the hammer is pulled back to half cock so loading may be done, it clicks but the hammer will not stay back. Thus causing other problems as well.

It's a black powder colt army.

Also the bolt is staying engaged during the full cycle of the hammer being drawn back. It only drops for a split second when the hammer reaches the point where half cock "should" be, the bolt pops back up (causing some go awful bolt drag lines:eek:)

James K
May 4, 2012, 04:07 PM
The first problem is either a broken trigger or the half cock and safety notches on the hammer are worn or broken. That is often the result of too light a pull so the finger does not have to pull hard enough for the trigger to clear the notches.

The bolt might be a separate issue or the hammer could be worn in that area also. It sounds like the gun needs an overhaul; if you choose to do it yourself and have little experience, I suggest you buy Kuhnhausen's book on the Single Action.


May 4, 2012, 05:19 PM
Let me add more stumping clues to the mix....the trigger and notches on the hammer are both like new and have little to know wear.

But.....There is a small pin on the very bottom of the hammer the catches the right "leg" of the bolt. It seems it's worn or just maybe too short to catch the bolt leg and may be slipping past the bolt. If I remove the barrel, backstrap/grip/mainspring and trigger guard; and with the bolt spring screw removed, placing lite finger pressure on the the "parts" (bolt, trigger and spring) the half cock seems to function fine, clicking into place and the bolt dropping into the frame.

May 4, 2012, 09:28 PM
The bolt should begin to drop soon after the hammer is pulled to allow the cylinder to rotate. Is the bolt engaged while the cylinder rotates, or does it move but then reengage?

James K
May 4, 2012, 09:42 PM
Take the trigger and hammer out of the gun and hold them in approximately the same position as they are in the gun. See if the top part of the trigger is thin and will fit all the way up into the half-cock and safety notches on the hammer. If not, then the trigger is broken.


May 5, 2012, 02:47 PM
with the bolt spring screw removed, placing lite finger pressure on the the "parts" (bolt, trigger and spring) the half cock seems to function fine, clicking into place and the bolt dropping into the frame.

Replace the bolt/trigger spring.

May 5, 2012, 10:16 PM
Might check if there might be a piece of perc. cap shrapnel or "smutz" in the internals blocking something. others have covered the rest.

James K
May 6, 2012, 04:28 PM
OOPS, my bad. I re-read my first post and then that the gun was an 1860 Army. The Colt percussion revolvers have no safety notch; they have safety pins in the cylinder (or should have).


May 6, 2012, 06:51 PM

The bolt VERY quickly drops out of place but then pops right back up.

I think the bolt/trigger spring is the wrong one or has been altered. It looks like the trigger side is shorter (or has been cut shorter) and it feels WAY stiffer than it should..are the springs on the BP colts and 1873s interchangeable? If so when that wolff set I ordered for my cattleman arrive I'll try the bolt spring in it and if it works I'll just put them in it, instead of the Uberti.

May 6, 2012, 08:57 PM
Someone else correct me if I am wrong here... There is a pin on the hammer that pushes up on the tail (rear section) of the bolt. The tail of the bolt rides up on this pin then falls down (under spring pressure from the bolt/trigger spring). This controls how long the bolt stays disengaged. It should drop down out of the cylinder notch quickly to prevent the cylinder from binding, then snap back up at the beginning of the trough leading into the next notch. When the hammer falls (and hopefully the gun goes bang) the tail of the bolt springs sideways to allow the pin on the hammer to reset under the tail. Either the bolt tail is not long enough or the hammer pin is worn down causing your bolt problems.

The two legs of the trigger/bolt spring are not supposed to be the same length: the bolt leg should be shorter. Check the hammer to see if the half-cock notch exists or if its broken off. Also look to see if the sear end of the trigger has been polished or filed upon. I suspect this gun is the product of a failed trigger job.

May 6, 2012, 09:48 PM
the hammer/trigger notches look fine.....that pin on the bottom left side of the hammer looks VERY worn.

James K
May 6, 2012, 10:04 PM
TrailBlazin is correct on the way things should happen, in a Colt percussion gun (OK, except the Root models) and the SAA and clones.

If the cam in the hammer is worn, the toe of the bolt might be slipping off to the side rather than off the front; that could mean the bolt will come down then either not clear the cylinder at all, or will come right back up, sometimes before the cylinder can even turn. That cam stud is not made as part of the hammer, it is a drive fit into a hole and can be replaced, although in most cases it is easier to just buy a new hammer.

When tuning an action of that type, one of the common techniques is to feather both sides (springs) of the bolt (on the inside) as well as the bolt spring itself. It doesn't need to be so strong the bolt dents the cylinder, but most are.