1911 Half Cock issue

[Laudanum]

Working on a project gun. Colt MKIV series 80. Not a sample of Colts finest work. Problem is that the trigger pull drops hammer from half cock. I know this would be normal if it were a series 80 hammer but it's not the original series 80 hammer with the low/flat half cock shelf. The disconnector, sear and hammer were all replaced. Safety parts were removed and a shim installed in place. Trigger appears to be original ... low, serrated, no overtravel adjustment. The hammer does not follow and grip and thumb safeties work as they should.

Dumb question maybe but can someone point me in a general direction to look to remedy the hammer falling with trigger pull from half cock?

Thanks

 

[BBBBill]

I've seen lots of shallow/narrow half cock notches that would not allow the sear to enter the notch. Also the rear facing side of the sear may be riding on the front of the hammer. That would limit the sear from rotating back far enough to drop in the half cock notch. What causes that? Different specs from different manufacturers. If the hammer and sear were from different manufacturers, the chance of this problem is greater. It can also be due to an out of spec part slipping through.
assemble the hammer and sear on pins outside the frame. Look at the under magnification while you manipulate them through the range of movement.

 

[Jim K]

Also check the shim; it can interfere with the sear if not made properly.

Jim

 

[Laudanum]

Sear/hammer look good on pins on outside of frame and contact looks good and even. The shim pretty much trashed the factory sear (burr around sear pin hole). I'm gonna play with some spare parts.

Thanks

 

[1911Tuner]

Normal. Colt Series 80 hammers don't have a captive half-cock notch. They went to a flat quarter-cock shelf that functions only as a hammer stop should something go wrong.

 

[BBBBill]

Not the original S80 hammer per the OP.

 

[Laudanum]

Posted this on another forum as well (thanks for the help on both BBBBill.)
Wanted to follow-up here as well. I dropped in a different trigger ... solid as a rock at half cock now.

More to be done but good for now ... thanks all. Very much appreciated.

 

[1911Tuner]

Not the original S80 hammer per the OP

Ah. Didn't see that part.