i've injected all 3 heads of the delts... i in no way consider myself to have large delts, but i like shooting the rear and side delts. i shot the front delts once and it felt a little wierd... i shot prop and fina (1.5cc total/arm) and they swole up pretty good. they looked pretty funny b/c i didn't shoot them in the exact same spot on each arm, so when they swole up they looked kinda deformed. since then i just stick to the sides and rear.