How can i change my parents mind?

ok...so i used to play airsoft when i was like 11-12 i was very responsible with it and never got in trouble with them or made stupid mistakes. then i was hanging around a few older kids well much much older kids and got in some trouble(had nothing to do with the airsoft guns). then my dad sold my collection(hundreds of dollars worth of guns) and i was done for a year. when i was 13 i started playing again but with cheap 50$ guns nothing special then i decided to stop then i sold those for very high prices to friends then with that money i bought a airgun which shoots lead rounds kinda like a .22 but very silent and backyard legal. now i am almost 14 and my birthday is coming in may and i want another airsoft gun just one i dont care to get a huge collection going just want one to play with my friends. now my dad is very against it he's not against guns so much as just shooting at eachother with guns that can be dangerous if your not responsible enough. and he just dosent want anyone to get hurt,you know reasonable stuff. i understand that and all but the thing is i was very smart with it i always wore eye protection never did close up shots and he knows that but he still says no. last night i asked my mom and she said no but she dosent care she just says my dad will say know but i havent asked him yet. i plan on asking him as soon as possible but i have no idea what im gonna say or how il bring it up. i NEED help on this and would really apreciate a good answer.........I DONT WANT ANY REPLIES SAYING; i think you need a new hobby or guns are bad or you should save your money or anything like that i know what i need/want. also my dad is very very tough to convince i have almost never convinced him to do anything or change his mind and when i try i get pretty far but fail. i also dont want answers saying ;your dad may seem hard to convince but thats kuz ur young........thanks for who ever helps