The UDP-9 and UDP-45 utilize the same pin setup as a standard .223/5.56 AR-15/M-4 and will work with any Mil-Spec fire control group. Most aftermarket triggers will work, however, some use a hammer design that is too short or a heavier hammer spring and do not reliably reset with a PCC BCG. Geissele, ALG & La Rue fire control groups have known compatibility issues with PCC bolt carriers. We do not recommend using any miltu-stage fire control groups.
We do not have any testing data as to the compatibility of any binary trigger system nor do we plan on testing them. From our communications with current binary trigger manufactures, some PCC BCGs will need to be modified in order for them to work with the binary trigger systems currently on the market.
We currently recommend using CMC Triggers pistol caliber trigger if you desire an aftermarket trigger.