I have this one 1911 that sometimes will drop the hammer to half cock, instead of firing, when I pull the trigger. I've tried to see if the half cock notch sticks out further than the other notch, it doesn't appear to. Can't figure out what would cause it to do this sometimes.

I would look at your dis-connector and the sear. Also check to make sure the slide is fully forward when this happens. If the slide does not go fully into battery the hammer with drop to half cock.

Adjust your over travel screw in the trigger.

Need to allow more overtravel by backing out the ge screw slightly that is in the trigger.. Well most triggers

I had to look that up.  None of my 1911's have one of those. '43 M1911A1 and a modern clone.  Learn something new every day.

It's not stopping at half cock it's falling from full cock to half cock.  Either your hammer full cock notch has worn or your sear has worn or hopefully the sear pressure portion of the three leaf spring needs to be adjusted to put more pressure on the sear.

Ooops, looks like I mis-read the OP but make sure it's not what I explained anyway.

In addition to insufficient overtravel, I've seen this happen when the left finger of the sear spring is not quite long enough and sometimes slips under the sear feet.

First diagnostic tool.

What was the last change you made?
How far was the over-travel screw?
You did measure it and write it down; right?

Had one do that the other day, replaced the three leaf spring, that fixed it. Found the the sear slipping off the disconnector (more specifically low spring tension was allowing the disconnector to slip out from under the sear allowing it to catch the hammers half cock notch)

Yep, I've seen that too.  Often it's just the way the middle finger is bent that does it.  Putting a little more (or a little less) bend in it can often fix it.  Too much curve, and the spring can bottom out on the trigger stirrup and fail to keep tension on the disconnector as it rides up.   Not enough curve can fail to put tension on the disconnector because it meets it at a poor angle.

Bend and try.
Bend gently.
Kinks are bad.

My son's RIA started randomly either allowing the hammer to follow the slide or stopping at half cock.  He initially thought he was limp-wristing it, until it decided to stop working completely.

Sitting at my bench, I couldn't get it to do anything consistently, but it was clear that the sear wasn't catching.  The gun was new, and I could have sent it in, but instead I just ordered a Wolff standard sear spring.  When the new spring came in, there was a distinct difference in one of the legs of the original spring and the new spring - the sear leaf wasn't as beefy and was a bit shorter.  Maybe the original spring was able to move around inside the frame, or maybe it just wasn't "right," but it was obvious that it was the problem.

It took plenty of the bend-try-bend again fitting to get the trigger, the disconnector, and the sear to work together, but that was sort of expected.  I have the original on my bench, sort of a trophy of fixing that pistol.  Today it shoots great and is as reliable as you expect a 1911 to be.