Assuming your shooting technique has not degraded and after verifying your bow’s specs have not changed (i.e. axle-to-axle, brace height, draw weight and length) number all of your shafts with a Sharpie pen. Then, shoot your groups and make note of where the various numbers strike. An enlarged group may actually be two groups over-lapping.
Another check would be to weigh each of those completed arrows. Different weights have different flight times. Even though all of your arrows may be of the same brand, model and spine, manufacturing techniques and specifications may have changed over the years resulting in different shaft weights.
Information I received from Easton Technical says they have yet to receive a set of arrows that has had the spine "shot out of them"; however, carbon composite shafts should be checked very regularly for damage by twisting and flex/rolling. This is particularly true after impacting with hard objects.
I personally use alloy shafts (Easton X-7 and Platinum Plus XX75's). I have always figured if the difference between success and failure was a camo shaft, I was doing something else horribly wrong.
Good luck and be sure to report back with what you’ve found.
K
