I’m not too sure it’s the gun. From the last range trip report it sounds like a bad batch of Federal SMK that lacks enough powder.
That one batch of Federal lacks the power to fully cycle the bolt, thus the failure to reload and lock bolt back on empty mag. But if works with all the others. Toss that batch and ask dealer/store for refund on bad Ammo.
If it were your piston it would occur with all Ammo unless you have compressed loads in all your other bullet types creating so much gas expansion force that it is blasting your piston back regardless of the alignment of your piston rings. Although I do advocate for ensuring your rings are off-set every time you clean and shoot.
Just me layman’s $0.02.