Confused on broadhead weight

I'm taking my 10yr old on a bow hunt in a couple of weeks and started looking at what broadheads I have that would work for him. I've always been a fan of the Magnus Stinger and have about 15 mix/match together in my broadhead box. I pulled out my reloading scale and started weighing them and the results confused me.

I knew I had some 125gr for my recurve and 100gr for my compound. The 125gr weighed closer to 129gr each and the 100gr weighed a pretty consistent 113gr - 114gr. Did Magnus put out a 115gr and I just don't remember buying them or are the weights that far off?

what poundage is he pulling?

It's not unusual for them to be 5% or so off in weight.

The 15gr difference my be the bleeder blades

Right at 28#'s. I've got some 100gr Montec's I thought about using as well.

The best thing I can tell you is to have him shoot the BH to see which will fly true.