I would like to have a piston with a delrin ring on the rear of the piston, however l'm thinking that using a standard piston as a starting point isn't the best as they tend to be quite undersize towards the rear and they appear to be made from some fairly soft material.

My plan is to machine one up from scratch but l'm not sure of the best way of attaching the trigger latch rod.
The original seem to be splined and pressed in but could l thread it in and pin it in place?

I would also try to make it a bit lighter as well.

Anyone made their own piston before?