Well, since AEGs in the airsoft world are all based on real weapons, aside from some exception like ECHO1's rifles, it would help if you had a model in mind.
By really small rifle, do you include SMGs such as the MP5? Another option could be the Kac PDW, but as I said, it's hard to help you when I don't know what to suggest.
K3vX | Airsoft Gunsmith/Gun doctor in training.
Feel free to contact me in your preferred language and I'll gladly answer.