I found out today that the piston for the CA25 (SR25 is longer than the standard M4 piston, thus I am waiting on the new piston to arrive at AZ paintball depot from the factory, In searching for this longer type piston I have only found the Classic Army Factory Piston, and a SR-25 Piston from G&P If any one else has or does stumble across this larger type piston from a differant manufacturer/company please let me know, as these are the options I'm limited to for now, also the CA25 has a re-inforced piston head. Just wanted to share my new findings