[ILLusion]

I would recommend properly modifying the part blow back unit to fit so that you can fully secure it to the slide. Having it loose will cause inconsistent performance as well as an irregular wear pattern to all contacting parts. As the slide moves back, the blowback chamber will wobble around in the slide, causing excess wear. Several tens of thousands of rounds through the pistol later, it may be extremely wobbly in there.

Tyson's recommendation to file the back of the blowback unit so that it sits up more is the most ideal solution.

I've also experienced the trigger issues with the SD frames, and I solve them by adding just a small 4mm wide pad of paper on the back of the stirrup where it pushes on the sear trigger. Vary the thickness to get the pull length you want. It's possible to adjust the pad thick enough that a pull as little as 1mm is enough to trip the sear and fire a shot. However, I highly don't recommend doing this as it is a safety hazard. Your gun may go off in to full auto with the sear unable to catch after a bit of wear. High powered GBBs unexpectedly firing full auto can cause significant muzzle climb to have the muzzle shoot in unsafe directions when you least expect it.

I personally use cut up Post-It Notes (I know, it's not an ideal situation, but I'm just working with the materials I have on hand!). Multiple layers of it can adjust the trigger pull length.