I’ve got a PSA lower with a geiselle ssf that I had to clearance some of the sidewalls of the receiver out to get my dias to drop in. While the sear is out it functions as you would expect but when I stick the sear in the trigger is dead in both semi & full auto, with the exception of charging the gun pretty hard it will allow the hammer to fall with the pull of the trigger. Is the a timing issue? The sear works perfectly in my colt SP1 with a stock upper and a stock GI trigger.

Sounds like it....  shim it to get it to sit a bit further to the rear

When DIAS is in, does it catch hammer when it is reset? I am referring to upper open and you manually push hammer back like B/C would.

It does, I would take a picture but I ended up dropping the gun & sear off at my local gunsmith to take some more metal from the receiver to give me more room. I couldn’t get the sear to sit all the way to the rear of the receiver just enough for the takedown pin to close then when I popped the upper off after racking I noticed the front half of the sear body would be sticking a hair higher so I’m thinking I need more material removed from the receiver.


Edit:actually do have a couple pics , the first two are my PSA lower showing where I had to file some just to get it to slide down in, but does it look like it’s sitting back far enough? The second two pics are showing how it fits (and functions) perfectly in my colt SP1 lower

I ended up fixing the issue by getting a different receiver with that little bump out in the inside (sear block I think it’s called) and that kept the Dias in place better and stopped movement forward and back which I think is what my problem was. Now I’m trying to get my CMMG drop in .22 kit to work. Not getting it to fire so I think the trip needs moved rearward. What are you guys using for shims?

I superglue the flat portion of a nylon cable clip to the take down lug to use as a shim.

https://www.homedepot.com/p/Gardner-Bender-3-8-x-1-4-in-One-Hole-Plastic-Cable-Clamp-18-Pack-PPC-1525/100158293

As for FA .22, I use hot ammo (mini mags) and Lakeside extra power recoil springs to brute force the system to work.