Welcome to the forum GWW! No doubting the 223/5.56 will be cheaper to shoot and have quicker recovery time in run & gun competition than 6.5 Grendel. In precision rifle matches where distances are longer the 6.5 Grendel will have an advantage. It is a lot easier to see and hear hits on steel targets with 6.5 Grendel compared to 223/5.56.
I find I shoot a lot more 6.5 Grendel than I do 223/5.56 but Im getting older, retired and dont train for CQB like I used to. I still shoot a lot of 22 LR out of dedicated 22 LR AR-15s for CQB, target and plinking.
I say get both if you can afford a 6.5 Grendel and 223/5.56. I reload so I dont have to worry as much for the availability of factory ammo. I stocked up over the last few years so Id have reloading components during the next drought. I have made a couple of trips to Sierra factory in Sedalia, Mo and bought factory second/blem bullets. Ive had good luck with these bullets for shorter range shooting. I watch for sales on bullets and other components. Starline Brass is next door to Sierra but it is cheaper to buy online brass from Starlines website. Watch Starlines website where they permit back ordering 6.5 Grendel brass. The brass usually ships within a few days after ordering.
You can also buy overruns and blem Nosler bullets from Shooters Pro Shop.
https://www.shootersproshop.com/
The 6.5 Grendel is a better hunting cartridge than the 223/5.56 and the 6.5 Grendel is good for varmints. If I had to choose one caliber for doing what I want to do it would be 6.5 Grendel. Prior to the last panic hunting ammo and quality target ammo was not that much cheaper in 223/5.56 compared to 6.5 Grendel. Bulk 223/5.56 ammo in 55 grain FMJ was always a lot cheaper to shoot than 6.5 Grendel (except when Wolf steel case 6.5 Grendel was cheap).
I am careful and dont loose many 6.5 Grendel brass so I can reload it several times. The 6.5 Grendel only uses 27-31 grains of powder which is still cheaper than the 308, 6.5 Creedmoor, 243, 22-250 size cartridges.
I find I shoot a lot more 6.5 Grendel than I do 223/5.56 but Im getting older, retired and dont train for CQB like I used to. I still shoot a lot of 22 LR out of dedicated 22 LR AR-15s for CQB, target and plinking.
I say get both if you can afford a 6.5 Grendel and 223/5.56. I reload so I dont have to worry as much for the availability of factory ammo. I stocked up over the last few years so Id have reloading components during the next drought. I have made a couple of trips to Sierra factory in Sedalia, Mo and bought factory second/blem bullets. Ive had good luck with these bullets for shorter range shooting. I watch for sales on bullets and other components. Starline Brass is next door to Sierra but it is cheaper to buy online brass from Starlines website. Watch Starlines website where they permit back ordering 6.5 Grendel brass. The brass usually ships within a few days after ordering.
You can also buy overruns and blem Nosler bullets from Shooters Pro Shop.
https://www.shootersproshop.com/
The 6.5 Grendel is a better hunting cartridge than the 223/5.56 and the 6.5 Grendel is good for varmints. If I had to choose one caliber for doing what I want to do it would be 6.5 Grendel. Prior to the last panic hunting ammo and quality target ammo was not that much cheaper in 223/5.56 compared to 6.5 Grendel. Bulk 223/5.56 ammo in 55 grain FMJ was always a lot cheaper to shoot than 6.5 Grendel (except when Wolf steel case 6.5 Grendel was cheap).
I am careful and dont loose many 6.5 Grendel brass so I can reload it several times. The 6.5 Grendel only uses 27-31 grains of powder which is still cheaper than the 308, 6.5 Creedmoor, 243, 22-250 size cartridges.