I've got a 30 mm inert round I bought from the USAF A-10 west demonstration team when they were at reno a few years back.
They were selling them for 25 bucks. They reload the case up to 4 times (marking the bottom of the case around the primer each time it is loaded - in a similar manner that is shown in the gunbroker photo...). After the case was fired 4 times, they loaded the empty case with an aluminum replica projectile and sold them at airshows. Proceeds went to the squadron xmas party.
They were selling them for 25 bucks. They reload the case up to 4 times (marking the bottom of the case around the primer each time it is loaded - in a similar manner that is shown in the gunbroker photo...). After the case was fired 4 times, they loaded the empty case with an aluminum replica projectile and sold them at airshows. Proceeds went to the squadron xmas party.

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