Yeah, there’s no way this thing is putting out 300 lumens, nor it is getting a “regulated” output on high for 4 hours. Of course, the ANSI specs don’t require a regulated output, so it could very well be down to 10% output at the end of 4 hours, and still be within specs.
But 300 lumens on a AAA battery? I have a hard time believing that. Maybe that’s the number if you stick a 10440 lithium-ion cell in it?