Hi,
I've been re-tuning my hunting bow and it's amazing how a seemingly minor thing can have a huge affect on accuracy. Something a inconsequential as a different release can really affect the P.O.I., whether it be field tips or broadheads.
Another thing is where your center-shot is set up. Everyone is different. What works for someone else might not necessarily work for you - even if the center-shot looks to be set properly.
That's part of the reason that i love this sport - it's so individualistic. Just setting center-shot and the nocking point is only the beginning of tuning your equipment for your personal shooting style. Great fun.