Are these two shafts the same diameter? Would the 100 grain brass inserts that are sold for the Axis shafts work in the Epic ST shafts as well? There seems to be a noticable price difference between the two and trying to figure out what the differences are from one shaft to the other.

The brass inserts from the axis will not fit.
You have to go with steel broadhead adapters and heavier broadheads or field points, to do the same thing. Bought some epics and was a little dissapointed with the adapter issue, good arrows, just some grief that I was not expecting.

Terry

Bowshot is right. These to models do not use the same insert. The Axis uses the HIT insert that you epoxy inside the shaft. The epic uses the older style of insert that you can hot melt in.  I shoot the epics @ 3ds since they are cheaper. To get the weight closer I stuff the epics with rope to increase total weight.
HTH