i think its so they wont open mid flight. when i used to shoot rage i never had problems with them opening mid flight, i just got sick of replacing the o-rings. i would test your rage out just to make sure there is no premature deploying of the blades. if they open mid flight i would just switch heads, not waste money on a shock collar.
Marlin XL7 .270 win
Mossberg 20 gauge 500 field
Winchester Model 1897 12 Gauge Modified Choke
Winchester Model 1890 .22 short
Bear Charge 70# 310 fps
Savage .223 O/U 12 Gauge Turkey Combo
Ruger M77 7mm Rem Mag