If you are just going to play ,That meens many rounds though it :}I would say buy just about any typ of 223.You can buy a cheep one for around $300 .The shells are very cheep.You can buy them in bulk.

There are many good guyns out there ,I like a bolt action but I hunt.If you are looking to shot a lot of rounds fast go for a mini 15 or ar15 they are not the best down range guns but they are fun to shoot.