Make a lightweight "bolt carrier" and guide rail...that's where all the ooomph of the impact is coming from.
The Bomber Super Lightweight bolt is significantly lighter vs. the stock one.
In addition to just using a lighter material for the bolt, you could skeletonize quite a bit of it (a good portion of it is not structural). And skeletonize the guide bar/rail too.
Also...but out of steel...it's always a good move to replace the stock piston body (the stumpy black tube that e-clips onto the bolt) with a steel model (stainless in most cases since RATech makes the majority of them). The flanges of the stock one are prone to flaring, which will allow the nozzle to flop around, which will wear/crash the cylinder, etc... The stock metal that they use is soft. It's been done already though, and relatively accessible...so probably not worth it.
Crafting different charging handle knobs would be cool too...but that's not all that hard to do on a lathe. At flip down "G3 HK-ish" knob would be trick though...
Sweet work though on the stock plate. Machining swirls are mezmerizing aren't they?