I believe the plastic tip is to give you the in-flight ballistic properties of a roundnose but the terminal ballistics of a hollowpoint. Scotty
the plastic tip allows for better flight and I believe it will aid in expansion by pushing back into the pellet allowing it to open up more on impact. Lambchops the pellets your thinking of are the lead free these ones are thishttp://www.crosman.com/gear/ammo/14001
I hope they are not too heavy for springer use.
According to a review on the Crosman website on the 145 gr. Nosler there was NO expansion.... so regardless of why the tip is there, is doesn't appear to be helping with that....Bob