Ok its time to do some accuracy and range upgrades to my M4. First off I want to start with a tight bore barrel. So my first question is which would be better a 6.01 or 6.03. I clean my gun and barrel religiously and I don't use full auto so im kind of leaning towards the 6.01 but tell me what you think. Next question is what brand of barrel should I get, what would be the difference between a madbull and Prometheus barrel besides the price. Next items on the upgrade list is a new hopup and bucking. Everyone says that firefly is the best but would a systema work? Feel free to leave the names of other brands as well, im trying to keep this upgrade under $80.