If that is the only scale you have available then it is the best you can do. And it is likely in the ballpark weight-wise +/- a lb or so. If you do it 3-4 times and come out the same difference then I'd call it 44 lbs.

They average about 40 lbs as it is normally a heavy weighted melon, some as high as 50 lbs. have been reported.

Dave