[MadMax]

Have you tried observing the sear movement? You can remove the rear grip safety spur (dingus that your thumb wraps around) to open a space so you can directly observe the sear and hammer engagement. The 1911 series of pistols is fairly easy to troubleshoot because of this feature.

You can simulate the recoil cycle manually actuating the slide and hammer with the following scheme: mag with no gas or bbs loaded!

starting conditions: rack slide to cock hammer and allow slide to return to battery

1. pull trigger to drop hammer, MAINTAIN trigger pull (keep the trigger depressed)
2. keeping pressure on trigger, slowly rack slide and observe sear movement while hammer is being re-cocked
3. observe disconnector movement to see if trigger bar is being decoupled after first third of slide motion
4. fully rack slide and slowly allow it to return to battery
5. observe sear engagement with hammer on forward stroke

It is important to maintain trigger pressure throughout the cycle to properly simulate the practical recoil cycle. The recoil cycle is very fast, a typical trigger pull will have you applying pressure throughout the entire recoil cycle instead of letting go at the exact moment of hammer release.

I suspect that either Hitman is correct in questioning the leaf spring placement (usual problem) or that you have a disconnector related issue. It's possible that an improperly sized disconnector tang or bent trigger loop could prevent the hammer sear from properly re-engaging the hammer with the trigger pulled.

Sometimes the hammer stays back when returning the slide to battery slowly, but snaps forward when the slide is released rapidly. If this issue is sporadic, it is often caused by the disconnector not being pushed down far enough to disengage with the sear or friction in the sear pivot. You have to be very careful when installing aftermarket trigger/sear related parts. There is often a bit of fitment involved to get things cooperating just so.