Sarpa and Redeemer pellets currently cannot crit, regardless of any mod set-ups. This has been mentioned before, but nothing conclusive was stated.
As stated in this post, neither the wiki, also nor the in game information, have actual information on gunblade pellet stats. This bug thread is being created in attempt to get any DE staff to ordain whether or not gunblades' pellets are supposed to have a crit chance.
~~>To clarify for anyone who will attempt to claim otherwise; watch th