To some in political positions, it could be considered an excess of quantity for the average game hunter not giving thought to the 2nd amendment.
Or practice. You can burn a lot of rounds pretty quickly with a light recoiling weapon like an AR-15, or an M-1 Carbine. I did buy 1,000 rounds of the latter, several months ago. Haven't fired a one yet (of that lot). Only have a 500 round box of .223 on order... but I don't yet have a .223 rifle, only a striped lower receiver, the rest is "on order".