6.5 Grendel versus 6mm ARC for whitetail

[LRRPF52]

I know this is an older post, but I am thinking about my birthday or Christmas wish. Listening Santa? A good 6.5 Grendel Bolt, or a 6mm ARC upper. I am not a frequent 1000 yard/meter shooter. but i do hunt. To be honest i am a 6.5 Grendel lover, BUT that being said, Hornady has the 6mm arc as compared to the 224 Valkyrie and the 6.5 Grendel. The 6mm ARC wins out in almost every catigory over the other two. Less drop and windage, and more foot pounds of energy, and more speed. Not a lot more than a Grendel, BUT if I were shooting long range, say over 600 yards, I would give the nod to the ARC. The thot for the moment is this one two part question. What will the 6 ARC become after as much time and development as the 6.5 Grendel, and will it ever be an intrest on a large enough scale to even begin doing so. Not much 6mm ARC shelf ammo. The 6.5 grendel has a decent amount of companies selling it. Hand loaders are lovin the 6.5 Grendel and seeing its limits easily surpass any shelf ammo for it. As for the 6mm ARC in a bolt, I would just go with a good old 243 Winchester with 50 grains of powder compared to 30 grains for the 6mm ARC, and 243 velocities ranging from 2900(90 grain boolit)-3900(50 grain boolit) feet per second vs 2300-2750 feet per second for the 6mm arc. Of course those velocities are with 20 inch barrels.The 243 is known as a white tail deer slayer when using a 90 grain boolit. Watched my bro inlaw drop more than a few bucks with a one shot knockdown, with not more than a short leap and face plant. Oh well, decisions, decisions decisions.of course those velocities are with 20 inch barrels.

If you had the same rifle set-up with both cartridges shooting the same bullet weight/construction, I don’t think you would be able to tell the difference on medium game within 300yds. For calling-in and shooting coyotes, they both work and are flat-shooters with 85-110gr weights from the same barrel lengths. BCs will favor the 6mm in those weights for sure, but mv will be higher with 6.5 Grendel. I just ran the numbers for two 20” guns.

20” 6.5 Grendel AR-15, 105gr Sierra Blitzking, 2775fps, .421 G1 BC, 6300ft ASL, 80 deg F, 100yd zero

300yds 2305 fps 1239 ft-lbs -10.6” drop 5.6” drift

20” 6mm ARC AR-15, 103gr ELD-X Precision Hunter, 2720fps, .512 G1 BC, 6300ft ASL, 80 deg F, 100yd zero

300yds 2257 fps 1165 ft-lbs -10.2” drop 5.7” drift

Hornady lists 2550fps as the max load with a 103gr ELD-X from an 18” AR-15. I bumped it up to 2720fps for a 20” barrel just to give the 6mm ARC the benefit as a bias filter. I just caught something odd though. Hornady must be inflating their BCs because I used their doppler program with the 103gr ELD-X profile in their library in the program. It matches the 105gr Sierra Blitzking velocity at 300yds even when I fire them both at 2720fps, same atmospheric conditions. The higher BC 103gr ELD-X should really be walking away from the .421 BC 105gr Blitzking out of the gate, but instead, they match at 300yds. That’s Hornady’s Doppler Radar data for that bullet, not a theoretical BC program. It could be a combination of over-stating the BC for the 103gr ELD-X, while Sierra’s might be under-valued and they’re meeting in the middle.

This is all academic at this point, so the hunter calling-in yotes isn’t going to be holding fractions of an inch of wind or 1” of trajectory at 300yds. Looks like there might be some marketing going on with published BCs again.

There isn’t a 6mm out there that I’ve shot or spotted for at distance that is very loud when they impact steel.

I just haven’t seen anything boilerroom-wise that will push a heavier 6mm bullet fast enough to make it hit the steel with much authority from 600yds and further. If you talk to a lot of ROs, they will say the same thing about registering hits at distance for the guys shooting 6mms.

On paper, you can show ft-lbs favoring a 6mm 105-108gr with the mid- 0.5xx region G1 BC, but once the projectile hits the steel, there isn’t enough mass to create the effects that are loud or make much of a visible impact. They’re very easy to connect with though, just not impressive when they connect.

With 6.5mm in the 90-110gr class of bullets, you hear the same thing, but the BCs are lower of course. Once you step up to 123gr, the impact effects are both audibly and visibly more noticeable, even from my 12” Grendel. 6.5mm just hits the steel harder in that weight class.