Silly question: which 30 cal for my next AR? 300BLK, 308 or 7.62x39?

[crosseyedshooter]

And I thought maybe I was getting older because my LMT with 18” stainless barrel, 3-15x scope, bipod and suppressor is getting a bit heavy for me!

[dpete]

If you don't reload, subsonic Blackout in commercial loads is hit or miss whether or not it stays subsonic. It really shines when you can roll your own and create a load tailored to your rifle. This is just personal preference (everything is) but instead of a shorty 308, I would do a short 6.5 Grendel. You didn't say whether you hunt or not, but a 12.5" barrelled Grendel is a treat to carry and still packs plenty of wallup. You can use your 30 cal suppressor on it too. I will grant you that ammo is harder to find for it than a 308 but being the smaller AR15 frame a comparable sized rifle in Grendel is going to be lighter than a 308.