223 can be great for deer also. ive killed a lot of deer with it.
People have shied away from the grendel some because its just not THAT much better than a few other options, and really isnt anything when compared to the large frame AR caliber options.
people praised the grendel when it came out as some revolutionary stuff. many, like myself, got into it, decided it wasnt really worth the cost of different bolt, different mags and ammo, at the time. its more common now, but its not so special that i need to be invested in another AR platform and ammo for.
Yes .223 is fully capable but illegal for big game in my state.
CENTERFIRE RIFLES
a. Must be a minimum of .24 caliber (6 mm).
b. Must have a minimum 16-inch barrel and be at least 26 inches long.
c. If semiautomatic, the capacity of both the magazine and chamber combined cannot exceed 6 rounds.
d. Must use expanding bullets that weigh a minimum of 70 grains for deer,pronghorn and bear, 85 grains for elk and moose, and have an impact energy (at 100 yards) of 1,000 ft.-pounds as rated by manufacturer.
HANDGUNS
a. Barrel must be a minimum of 4 inches long.
b. Must use a minimum .24-caliber (6 mm) in diameter expanding bullet.
c. Shoulder stocks or attachments prohibited.
d. Must use a cartridge or load that produces minimum energy of 550-ft.-pounds at 50 yards as rated by manufacturer.
I built my 6.5 Grendel mainly to try something different in a AR15 platform and being a legal caliber to hunt big game with is a plus.
Guns are like tools, there's one for every task and some can be used for different task effectively.
Seems many of the new calibers (.22-.30) coming out offer slightly improved ballistics as more mainstream traditional calibers but most IMO aren't improved on to warrant adding another caliber to you collection.
There's a lot of interest in 22 Creedmoor (6mm Creedmoor parent case) and 22 ARC (6.5 Grendel parent case) but when you already have calibers that offer similar performance it's a tough sell.