How interesting. I've seen the "rebound" phenomena at the end of the permanent channel in calibrated ordnance gelatin tests before- looks like another commonality that this clear gel seems to have with ordnance gelatin.
Just for grins, I ran your test data -recovered average diameter and weight, recorded impact velocity- using the Schwartz bullet penetration model and got a predicted penetration depth of exactly 11.25 inches which is exactly how far your test round made it before it rebounded. Looks like the clear gel data fits models that correlate strongly to ordnance gelatin- very impressive!
Thanks for the great test.