Yes, I'm surprised too that it's so tail heavy. A review of the Venus 40 available on RCU shows the author balancing it with the battery around CG with a OS 50sx, which is comparable in weight to the Magnum. I am measuring 4-5/8 behind the leading edge, or if I remember correctly 118mm, which being from Europe, feels more familiar to me.

I don't understand why it's soo tail heavy. All I did was glue the tail feathers on.
Oh, well...[]

-tychoc