I'm familiar with Glock's program and not the others, so the following is the Glock method of purchase:
- You can order from Glock-USA by filling out a form (posted here on NES) and providing required documentation and a check. It gets shipped to PD or MA Dealer for NICS/FA-10. YES, officers MUST pay the FET (only gov't agency purchases are exempt).
- You can order from a Glock LE Distributor, do the payment and documentation with the distributor and have it shipped to a MA Dealer for NICS/FA-10.