PSA rifle getting better

[FRB6.5]

I just bought a 12” upper and it shoots like junk. I was awfully excited to get it after reading all the positive reviews. I’ve changed ammo and still can’t get better than a 3-4” group at 100yds.

Their stainless uppers and guns have an accuracy guarantee, document what you did and used and contact PSA to send it back. You won't do anything to "tune" that to shoot MOA, it is just a bad barrel.