It didn't up load so here's the link https://drive.google.com/file/d/1j_3oFT3btxOaGFL2aUVwgEhizPpV_aSp/view?usp=drivesdk

I just realized before posting the link that I only partially assembled the setup. It was supposed to have a length of seamless metal tubing as part friction reducer part concentricity control in concert with a end plate the piston indexes against.

Despite omitting these two seemingly crucial components the piston indexes on button headed m3s lock nutted at equal height and even works albeit with multiple stoppages. Although it could be from the ill assembled muzzle device (it's not doing any favors im sure) I believe it more likely to be an incorrectly matched recoil spring given the failures were always with the subs making it cycle just enough to extract the empty shell without enough rear speed to throw the shell free of the slide often getting caught in a double feed situation.