If I see a bit of a constriction mis-cue it's always in the youngest ones. Some quickly get the control the head, control the prey concept, others it takes awhile but none of them ever let the rodent chew them up. Some of them never do grab the head but coil so quickly right behind the head that the prey is safely held by them.
As long as your snake is eating an appropriately sized prey item and it's a healthy snake on a regular feeding schedule, it will figure it out.
Hopefully he figures it out soon
1.0 Normal Ball Python
1.0 Western Hognose
0.1 Brazilian Rainbow Boa
1.0 Hypo Columbian Red Tail Boa