Barrel length has an effect on bullet velocity and elevation affects how fast velocity drops. The altitude you normally shoot might significantly affect ballistics to where one barrel length might prove to be the best for the elevation and terrain. Here are some velocities I got using a Magnettospeed Chronograph on a 70 degree day at 450 ASL. If you use a G1 BC .510 for this factory ammo velocity with the height over bore (2.5 for 1 scope on AR-15, 2.75 for 30 mm scope on my AR-15s) you can use a ballistic calculator to see which barrel might meet your desire.
Im addicted to the 6.5 Grendel and have a 12 pistol, two 16, one 18 and one 20 AR-15 plus a Cz 527 with 24 barrel. I like them all and enjoy shooting them. Each build is kind of specialized but I just enjoyed buying and assembling AR-15s in 6.5 Grendel.
123 Grain SST Hornady
12 2277
16" 2430
18" 2493
20" 2511
24" 2583
The forum has members who have used the 6.5 Grendel extensively in places all over the world. The 6 ARC and 6.5 Grendel are so close I give the 6 ARC the velocity advantage and is probably a better long range target cartridge. The 6 ARC might be a smidge better as a varmint cartridge in some situations. I give the edge to the 6.5 Grendel as a better game cartridge but it might be hard to physically see the difference in any hunting situation between the 6 ARC and 6.5 Grendel. Lack of ammo and brass has kept me from getting a 6 ARC as I have my bases covered by one of my 6.5 Grendels. I have shot to 1000 yards maybe 4 times in ten years. At my age who knows how many times I might get to shoot that far again. It really depends on how your going to most use your tool.
Im addicted to the 6.5 Grendel and have a 12 pistol, two 16, one 18 and one 20 AR-15 plus a Cz 527 with 24 barrel. I like them all and enjoy shooting them. Each build is kind of specialized but I just enjoyed buying and assembling AR-15s in 6.5 Grendel.
123 Grain SST Hornady
12 2277
16" 2430
18" 2493
20" 2511
24" 2583
The forum has members who have used the 6.5 Grendel extensively in places all over the world. The 6 ARC and 6.5 Grendel are so close I give the 6 ARC the velocity advantage and is probably a better long range target cartridge. The 6 ARC might be a smidge better as a varmint cartridge in some situations. I give the edge to the 6.5 Grendel as a better game cartridge but it might be hard to physically see the difference in any hunting situation between the 6 ARC and 6.5 Grendel. Lack of ammo and brass has kept me from getting a 6 ARC as I have my bases covered by one of my 6.5 Grendels. I have shot to 1000 yards maybe 4 times in ten years. At my age who knows how many times I might get to shoot that far again. It really depends on how your going to most use your tool.