I don't see how they can be brought in at 7 1/2 lbs either, but lots of them are reported to be under 8 lbs.
Mine weighs 9 lbs. 10 oz. with a Magnum 91 four stroke for power.
I use a digital fish scale to weigh it.
It flies good but I am sure it would be better if it was 7 1/2 lbs.
At a minimum it would have much better vertical performance.