I'm trying to go the short stroke route on my Mk3 HC

Should a Mk2 Piston fit a Mk3 Compression Tube and work?

I assumed that because it has a longer latch rod, it should engage with the trigger sear sooner that a Mk3 - I also understand that the ABT might not engage.....this rifle is for target work only and not humped around the field.

I've tried it but it won't Cock.

Have I made a school boy error.......???

Cheers Steve