well im no expert on kevlar to be honest im not to sure how it works other then its like a webbing designed to catch a bullet. I talked to the owner of the gun store down the road about the five seven he has in stock asked him about the availability and what not he said that its the first one hes had in his store and actually bought it used from a friend of his who used it for jack rabbits and coyotes asfar as ammunition availabilty the only ammo he has in stock for it is hollow points and soft points he said that none of his distributors carry full metal jacket ammo for it and that hardly anyone even carries ammo for it and that finding fmj's would be like trying to find a needle in a hay stack. also lead core full metal jackets arent even classified as armor piercing. its just the same old dilemna all over again I cant remember exactly but i think it was smith and wesson who chambered one of their revolvers in the .221 fireball and the antis were all over it like they are all over the five seven now. its just BS