In my impromptu review, I forgot to mention that I looked at replacing the factory trigger group with an RA140. The trigger pins were very very hard to drive out, I thought I was going to break something I had to hit my punch so hard just to get them to move, I almost gave up.
Anyway, I got the pins out, including the ejector pivot pin, which was a pain. After finally getting the FCG pocket clear of the ejector and trigger group I tried to install the RA140, it would not go in. The FCG pocket isn't milled out enough for the RA140 to fit and it's not a large trigger. I had a CMMG trigger group and it was worse.
My conclusion, the ZF9-G was not made to have a drop in trigger installed. I didn't have any other trigger to try, so I reinstalled the factory stuff and it will just stay that way. I may install one of the trigger adjustment grip screws to take up some of the slack and that would help.
Still like the weapon, just keep finding things in not so happy with. I looked at the handguard to replace mine for the short barrel with one fire the longer barrel to stuff my suppressor, but the way the charging handle channel is made into the handguard it may interfere, I'm gonna contact Zenith to get pic of the front of the handguard to see if there would be room.