Like the X10, the A/C/E is a barrel shaped shaft so it tapers at the ends. On both these shafts there is a long parallel section in the front, then a tapering section where the diameter gets bigger, then a parallel fat section in the middle, then it tapers back down on the tail section to a final parallel section that is much shorter in the back end. If you cut the back end of the shaft it stiffens the arrow faster than the front. The more flexible tail section was really designed for the finger release of recurve finger shooters - the stiff middle helped the arrows recover faster. What compound tournament archers found pretty quickly was they were having better results with cutting an inch or two or three off the back and removing most of the weak tail section. This eventually led to the birth of the X10 Pro Tour which is actually a parallel shaft in the rear that is stiffer than the rear of the old X10.
The A/C/E shares the same aluminum core tube as the new Injexion. Also the Navigator arrow. Therefore, you can actually put Injexion components in the A/C/E and Navigator arrows and turn them into hunting shafts. I mentioned cutting length off the back of the A/C/E just to help stiffen the arrows since anyone shooting these for target probably was shooting a lot less draw weight than their hunting rig. I shot .430's forever before X10's so I probably have 6 dozen or so kicking around. Not sure if I can cut much more off them, but I usually shot them with 2" off the back so they are probably pretty close to .350 or .370 spine now anyway. The rule of thumb was that you would jump one spine value for each inch cut off. As I recall, A/C/E's come in .620, .570, .520, .470, .430, .400, and .370 spine - there are lighter ones too, but you wouldn't dare hunt with those.
If you aren't sure how much is cut off the tail, stand them on the nock end and compare to an uncut shaft. The logos are the datum point on the arrow so if the logos are lower on the cut shaft than they are on the new shaft then measure the difference in the logo to see how much is cut off.
Easton actually made an outsert and broadhead combo for this arrow back in the day - the thread was a 6-32. It didn't catch on... Low and behold, 20 years later and look what a bitchin' idea this is!!! Maybe they will go all the way and make the X-10 Pro Hunter!!! That would be the BOMB! And... I would happily launch them at unsuspecting animals many furlongs away.