NOt going to get scar tissue if you rotate sites and dont do multiple shots each day. Even doing multiple shots per day you can still rotate areas and not get any scar tissue. I suppose if you feel like you must go smaller than 23 gauge then youll want to be sure to use a 23 gauge to draw with and then the 25 to shoot with, otherswise its going to take several minutes to just fill the syringe. Youre better off anyhow using two pins per shot, one to draw and one to shoot, since it gets dull going through the stopper. If you have amps then you dont have to worry about that factor so much.