Unless I'm crazy, 70# should be 70#. I don't think draw length has anything to do with it.

I'd take a hard look at the string and cables.

I bought a used bow last year with 60#limbs and when it came it was maxed at 56#. A few of the strands in the string and cables had broken and both were severley stretched. New cables and a twist or 3 and it was sitting at 61# with a difference of almost 30 fps.

That sees like a LOT of weight to be missing though.
What kind of bow and the rest of the specs??

Trushot }}------>