80 percent lower Glock 17 gen 3 help

[Btp2332]

I came across a poly 80 lower. Drilled the holes and removed the required plastic. This particular lower does not use a metal rear rail system instead it comes with the jig and a bit to remove plastic to create a rear rail. I smoothed everything with different grit sand paper to make it smooth. I took the factory slide off a gen 3 17. Racks fine. Clearances look fine. Slide stop fine. Trigger seems fine. Trigger reset fine. I head to the range to test and the gun does nothing. I rack the first round into the chamber and the trigger does not move. I put all Glock store parts in the lower, any help would be appreciated.

[Danjojo]

Put up a couple pics of the frame from the top down and side. My guess is combo of the tolerances and flex with a loaded mag altering engagement. With one or two in mag it may fire. Try adding a dummy round in the mag starting with just one and see. Not all the Poly frames come out right.

[Btp2332]

Will do tomorrow. Got home late today. Thank you

[zaitcev]

I'd try at home with snap caps. Double make sure live ammunition is not near or in the gun, then pull the trigger. If it reproduces, then the usual attempts to smear with some ink or whatnot and find the interference.

[Btp2332]

Hope this works. I added a few pics

[Danjojo]

Can't see anything that is causing it, thought maybe another set of eyes might see something obvious.

Fully assembled, how much different is the effort to insert the same loaded mag compared to it's purebred cousin?

With slide on frame but without barrel and RSA inserted, how much slide play is there?

If it does dry fire with completely empty mag, then also with a couple dummy rounds/snap caps, I would think it has to be managing to disconnect the striker from pressure of the full mag.

[ViniVidivici]

I wonder if it's possible the uppermost extension of the trigger bar (the part that engages the firing pin safety) is bumping into, and stopping at it, instead of moving it up and out of the way?

I guess this could happen if the slide itself was sitting too low on the frame, or at a slight "rearward" angle?