What's up with my nelson?

My nelson has run perfect on a customized Sig 1911 lower for about a year and a half. The last 2 weeks I've had an issue where I go to shoot and the hammer is at half cock.

I don't think the hammer is failing to go back far enough due to weak ammo, I use CCI standard and have been primarily since I got The nelson. The reason I don't think its weak ammo is because I don't have extraction issues, stove pipes are almost non existent.

My next guess was hammer falling due to the sear spring relaxing. The problem is I can't get the hammer to fall by dropping the slide.

Any guesses? I've got a Volquartsen Olympic custom pistol I can use till I get the nelson back in order.

I'd take a close look at your sear/hammer interaction and make sure the left two leafs of your spring are providing enough resistance for your gun. Some guns can't handle 2lbs triggers using the stock sear and hammer. That sear/hammer hook interaction has to be just right to handle low trigger weights.

back your trigger stop screw out a half turn or so.

The Sig lower was worked on by Dave Panciotti of Evolution Armory, he is a gunsmith with experience working for both Colt Custom Shop and SIg Sauer.  He replaced all ignition parts with top quality components.

With that said I also suspect the sear spring.

Glenn. You're referring to the overtravel screw right?

yes

Sounds like nothing to do with your Nelson conversion. But while you're working on stuff make sure to clean your chamber and breach face.