Good score, I would practice some OPSEC on the how and where portion of the story. U.S. property is very seldom free to take, especially with GL getting 4-5.00 a can at auction.
Someone could get into more trouble than they know, having been a certified range officer @ Dix, those cans are required to be certified empty , with spent brass, and returned to the ammo control point prior to disposition, the disposition never included a ride in the back of a POV.
It has been my expirience that you aren't cleared (as a unit) until the spent brass and cans are turned in, at least that is the way the Army does it.
Always becareful of what you take for free, in the mid 80's we had an E-7 / WG12 AGR Tech get into alot of trouble for taking JP-4 from a fuel bowser that was used for defueling acft, he was burning it at home. CID got involved and it was a giant sh*t storm for 40.00 worth of fuel. They made an example to prove a point and it was ugly.
I'll have 30yrs this Sept. so I know of what I speak.
Just my 2 cents