These little gizmos are a personal favorite. The huge downside to the stock LPR is that it is unadjustable from the outside. This is a HUGE hassle when you're setting up your 'Cocker and you're in real trouble if you were to need to fiddle with your settings while on the field.

The Twister Kit from Besales fits on to the end of the stock LPR and allows you to adjust velocity via the Twister knob.