re: C/o 2017 Recruit

Some good drills I've seen that have helped 40 time is these two person resistance bands with bags on the ground to help with stretching out your stride and running with more power

But really, as a db, your 40 time isn't near as important as your ability to react and change direction quickly... So ladder drills and cone drills along with drills to work reacting under stress would be more beneficial IMO