You made the right choice already IMO. Every AR I've seen (and just about all other semi-auto's for that matter) made a MESS out of the brass! They scratch and dent the brass up enough that you only get one use out of it, so unless you REALLY, REALLY just HAVE to hand load them, that's just a waste
IMO. I've fed my AR10 several different hand loads out of curiosity, experimenting, and in learning the lesson about how bad it chews up brass. Only to find it LOVES Federal Premium factory made 165gr. ballistic tip, boat tails better than anything I could brew up.
I still recommend to do your testing the same way you'll do your shooting. Cold / clean bore with 4 more follow up shots. Use exactly the same POA for all shots in the group, and see where she puts them. I've got a .22 magnum that will throw the first shot after a cleaning 2-3" outside the rest of a group the size of a dime at 50 yards! I'm sure glad I learned it does this on paper. Not by missing game in the field.
Note: I HATE that gun, and it never leaves the safe.

Looks pretty though.

Stupid Marlin...