I have been carrying a Zero 1TC for two years now and love it. I shoot it well and it's been a great performer for me.

I really want a version without a threaded barrel, so I'm considering the Zero 1 compact. Does anyone know a machine shop that will mill for a red dot?

FWIW, I asked about a replacement non threaded barrel, but it will still protrude from the slide and only saves about .25". I'm not sure how they do their measuring, but my TC barrel comes in around 4.5" in length and the replacement they suggest is the full size length (4.3").

Here's the replacement barrel KVAR suggested.

They make a Compact Tactical now, that has a red dot plate and a threaded barrel. That seems to hit all your needs in the factory package.

That's actually the 1TC, I believe. That's the model I currently have but looking for a version with all of those features and no threaded barrel.

I wonder if a shop that does P226 slide machining could do the same for the Rex Zero.

I can confirm the compact barrel fits and functions in the 1TC setup.

I've found the 15rd mags are just a hair too short for my hands. So I also took the +2 baseplate off my 18rd mag and put it on the 15rd mag. It seems to function fine but sticks out forward too much. The 18rd with the basic baseplate looks good and works fine with the spacer.

I need to design and print a pinky extension for the 15rd mags.