A barrel roll is done primarily with the rudder and elevator. Use of ailerons gives an aileron or axial roll. There is a difference. But in answer to your question, Yes, a 3 channel is capable of it. Now whether or not your controls have the necessary authority to make it happen is another question. Dihedral does play into it. But all you can do is go up and give it a try. If it doesn't, more throw on the rudder and/or a bigger rudder can help. But some designs simply won't do one. At least not well.

In WWI a common practice for both loops and rolls was to dive first to build up some speed. So even the real ones can have trouble with the maneuver.