It's in today's paper, he had 23,000 rounds of ammo.
It's not surprising that they describe his stuff as a "cache" and not as a "collection."
He also is alleged to have grabbed a .308 rifle and locked himself in a bathroom when ATF agents came to his house.
It was kind of interesting to note the details made available in the article--the M-16A1 was described as having "US Property" markings, the rifle he grabbed was described as a ".308 rifle with a 10 round magazine," the difference between semi-automatic and full-automatic functioning was briefly explained, details were given about his former FFL, etc. IMO that's better than "machine gun," "assault rifle," "guns," etc. This writer apparently has some familiarity with firearms, or at least he/she paid attention to the source(s) of information.
According to the article, the M-16A1 was purchased from a "friend" on Kauai that so far Hamura has refused to identify. The article also noted that the rifle was not reported as stolen or missing.