An AR15 is a decent varmint rifle. It's caliber, .223, has nearlyHmm... I don't know about "ghost guns," but my brother got an AR15 kit via the mail. All the legal by mail pieces were shipped to him, and all he had to do is buy the remaining pieces from a third party seller to assemple his gun. I think the whole process cost him some $1,500. Seems like a waste of money to me... He doesn't even take the thing out shooting. It's just something he has that takes up space in his gun safe.
It's his money, but I'd rather just get a hunting rifle - something that actually has a purpose (outside of warfare) and is much more practical.
identical ballistics to the .222, which is....great for varmints.
I'd prefer a heavy barrel single shot rifle though. That's just me.