Eddie , Both myself (designer of the Hammer head) and the manufacturer ( Arrow Dynamics do not recommend bare shaft testing, I am not going to go into the logistics once again but take my word , most of the time bare shafting ADs will not work , yes some people have done this with good results, most have the same problem you are experiencing.
My suggestion is put on some feathers and try again.
Also you are correct that the Hammer Head was designed to be EFOC, the idea was to come up with an arrow that full length with an aluminum insert and a 125 gr. point would weigh in at 600 gr.
Cut them to 29 and use the same you would have 550 apx and could go from there with different weight points to achieve the mass weight you require.
This idea works from many weight bows for many different people ( not all).
Put on some feathers and try again