You can expect to take better advantage of a Varminter's accuracy if you reload. The only ammo that will come close to reloadings accuracy is fairly expensive stuff. Black Hills is reasonable, as is Winchester USA's 45 gr. JHP load. The cost IS an advantage if you consider 'varmint' or 'match' ammo runs upward of $0.75 per round. A reloaded equivalent can be made for less than a quarter.
You will achieve great accuracy by reloading your own, at reasonable cost. Consistency is key, but don't go overboard though with perfection.
I don't weigh cases. I simply keep brass lots seperate.
I have found that MOST powders will cycle the action as long as the charge is high enough.
Reloading for the AR WILL give you accuracy. Neck sizing is not the only aspect.
If you are already set-up for reloading, why not? It will only cost you for die and a shellholder. It'll pay for itself quickly.
Using $16/pound powder, LC cases, and $14/box bullets, you will be able to pay for a $40 caliber investment in as little as 60 rounds versus $18 per box ammo.
If you plink only, then it is up to you, but if you ever want more than a couple boxes of Grade A ammo that you know will hit a target, do it.