John Morales, the actor who played the crime-fighting cartoon character McGruff the Crime Dog, was sentenced to 16 years in prison stemming from a 2011 arrest in which police seized 1,000 marijuana plants, 27 weapons – including a grenade launcher – and 9,000 rounds of ammunition from his home.
The “launcher” is probably one of those under barrel AR-15 attachments which is trivial to get (expensive and might also require the steps below, but that’s a one time thing).
The grenades though:
To legally purchase, make, or possess a Destructive Device (DD) you must:
And you have to do the forms and pay the $200 for each grenade individually.