Yeaaaah I really can't recommend the AG lightweight bolt from my experience here. I mean the mis-fitting rubber piston head is one thing, but the tolerances of the nozzle guide being so janky that it actually knocks my hop dial and reduces hop by 1+ clicks each time is completely unacceptable. I've verified that my hop chamber is not loose or anything and the stock bolt has 0 issues firing without messing with the hop setting so I'm pretty sure something is faulty with the bolt. I've tried replacing the piston head with the one from my stock bolt and it fixes the friction between the nozzle and the bolt, but given the price I paid for this bolt it's simply not worth it. I really don't understand how you could ship a bolt with a nozzle set that literally does not work OOTB... Multiple people have had issues with the piston head this bolt set comes with so it boggles my mind that it hasn't been fixed.
The AG BCM MCMR rail I have however is great, I can't fault the quality there, but the precision required for a bolt I think is greater than that of a handguard.