Reloading for gas guns is different than loading for bolt guns, not prohibitively so, of course, but decidedly different. You can't just worry about pressure signs and accuracy, you have to worry about function too - worry about feeding and flow.
Most - if not all - of the off-the-shelf factory AR's these days, especially carbines, are over-gassed. I tend to think they do it on purpose to ensure reliable cycling and ejection, despite the excessive fouling and battering of the action. You can mediate that improper design, by either balancing your load to your gas system, or installing an adjustable gas block and balancing your gas flow to your load (better the latter).
Overgassed AR's (improperly timed) will reveal themselves via case damage: case head swipes, ejector impressions, extractor damage on the rim. They'll batter your buffer bumper and your extractor too.
Watch your ejection also, if brass is landing anywhere forward of your ejection port 12 o'clock to 3 o'clock position, then you're overgassed. If it's landing behind you between 4:30 and 6 o'clock, you're undergassed. 3-4:30 is where you need to be. Undergassed, you'll run the risk of failure-to-eject and failure-to-feed, overgassed, and you're beating up your gun and your brass for no reason, and you're wasting powder (losing velocity).
If your new AR is a slick side - i.e. without forward assist - then it's a good idea to buy a small base die. If your rounds don't feed, you won't have any recourse to coax the bolt to close into battery. I run uppers with FA's just in case, but I've loaded thousands and thousands of rounds for AR's and haven't really needed small base dies.
For powder, Varget won't disappoint. Benchmark, 4895, 4198, 748, and 335 will all treat you well also, just match up your powder with your bullet weight. I tend to believe that if you can't get 27.3grn of Varget under a 50grn V-max to shoot well in your rifle, your rifle is broken.
H4895 under a 60grn Partition keeps me happy for pig medicine.