Hornady Team Discusses 6mm ARC

[BluntForceTrauma]

Hornady’s team discusses the 6mm ARC in THIS YouTube video and at 15:14 one says, “Terminally, the goal of the original project was to meet or exceed .308 terminal performance at distance…. And it did exceed that…. When you went to 6mm, you had that.” Another chimes in, “That’s interesting: You picked up terminal performance by reducing the bullet weight and diameter — because of the velocity performance. So, now you have a warfighter that is equipped with the small, lightweight AR15-sized platform that’s been the standard, but you have all the external characteristics of the .308 Winchester at range.”

They're saying the same thing we've always said about the 6.5 Grendel, and now the 6mm ARC.

Obviously, Hornady's team is biased toward their own cartridge — and I really don't take their tech guy to be a flat-out liar — so I thought it was interesting they said 6ARC terminal ballistics exceeded .308 at range — never mind dispersion and hit percentage.

[biodsl]

What a bunch of salesmen.

With all due respect, they're speaking so vaguely as for it to be meaningless. Let me understand, terminal ballistics at range (which he will not identify), a 105-ish grain 6mm starting at 2650 is going to exceed a 175 SMK 7.62 starting at 2500-ish (20" barrel)?

Let's run the numbers:
6ARC subsonic at 1050 w/274 lb-ft
7.62x51 subsonic at 950yds w/491 lb-ft

If you want to say it stays supersonic longer, then say that. If you want to say it's effective at longer ranges, than say that. But don't expect me to believe that 274 is more/better than 491. Don't expect me to believe that terminal performance is better, unless you mean beyond the range the 7.62 can hit. That would be better external ballistics, wouldn't it?

[grayfox]

I'm sure some of it is salesman-talk.
But if you do apples to apples, say both at 950 yd, then the 7.62 is 491 ft/lb ke, and the 6Arc is 439.
That looks pretty close, now the momentum impact may differ but if ke is the ability to rearrange the innards of the guy it hits, they are pretty close to equal. Don't we always say that when an animal is hit, you don't worry about 50 ft-lb or so?

Not trying to sway the argument one way or the other, but just laying out a side by side comparison... "at distance" -- whatever that means! Definitely easier to carry and easier to send out a followup shot as sight picture would be less disturbed by the shot...

Even as a hunter/shooter (and not by any means an SOF or even regular Army/Marine trained guy!) there are plenty of places I would choose my 308 (or Creedmoor!) over grendel or 6Arc... but there might be some places I would choose the 6Arc first, as well.

I really enjoyed reading '52's account on the relatively miniscule place a "new rifle" program has in the grand scheme of DoD procurement dollars, and actual on-scene fighting materiel... interesting indeed!

[biodsl]

Grayfox...I get 347 lb-ft at 950 yards for the 6ARC. Did I do something wrong?
Hornady 105 bthp at 2650 at the muzzle, standard pressure and temp. Am I underestimating the velocity with an 18" barrel?

[grayfox]

IDK, let me double check...
Hornady Black ammo with mgspd in my barrel, Hornady 105 bthp, BC-G1 0.530, ok I used 2651 'cause I have it already in my pointblank ballistics table. (which actually is for my 20" Monster barrel... but who's looking? hahaha!)
Now it only uses G1's so I don't have any G7 performance data...
But in PB it shows 950 yds, -310.53 in. path drop, velocity 1372 ft/s, 439 fpe KE.
At 100 yds it shows 409 ke.

Could be the difference for g1 vs g7 maybe? g7 would be more accurate that's true.


[edit to add] my app is set for 500 ft elev, 70 degF.

To follow up on one of my comments, in the vid they keep the meaning of "at distance" classified - for good reason I guess. But my guess would be 800 yds/ maybe 750m if you're "click-happy." (lol!) the 7.62 would have some advantage in metrics at that yardage...

[grayfox]

Maybe in practical terms they are really saying, with a lighter-weight package they can reach out with enough KE to mess up the bad guy's innards at (my guess) 800 yds... to heck with metrics, does he fall over at that range when I hit him center-mass?
ps, at that distance I postulate that he took his hot and heavy "body armor" off since he figured he was out of range... well, he still doesn't know! (being dead) but his buddies know, bad choice guy!!! Hahahahahahaha!!!!!!!!!!!

[jasper2408]

Here is a comparison between 6mm ARC(Hornady 105gr BTHP), 308Win(Sierra 175gr TMK), and 6.5 Grendel(123gr ELDM) that I did in QuickTarget.
These calculations are from QuickTarget and QT Unlimited and therefore I do not know how accurate they are. Just thought it would be interesting to see on a graph.

Update: I decided to use graphs that showed the lines better. I also added the 123gr 6.5Grendel to the mix.

VELOCITY
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ENERGY
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[biodsl]

Here is a comparison between 6mm ARC(Hornady 105gr BTHP) and 308Win(Sierra 175gr TMK) that I did in QuickTarget.

Excellent. Thanks. A great illustration.

[jasper2408]

Excellent. Thanks. A great illustration.

You are welcome.

[Zeneffect]

how do you get multiple ballistic calculations out of quicktarget?

[jasper2408]

how do you get multiple ballistic calculations out of quicktarget?

I am going to move my response to a new thread where new comparison graphs can be posted. I thought that a new thread for QuickTarget would keep this thread on topic and not about QT.

[Zeneffect]

Save as reference. That's what I was missing.

Thanks

[jasper2408]

Moved this response to the "Using QuickTarget" thread.

[lazyengineer]

Here is a comparison between 6mm ARC(Hornady 105gr BTHP) and 308Win(Sierra 175gr TMK) that I did in QuickTarget. The bottom 2 lines are the ft/lbs and they reference to the scale on the right and the top 2 lines are velocity and they reference to the scale on the left. The bottom scale is range which is 1500yds max.

This graph is at 200m elevation(Ukraine), 70 degrees temp and give about a 200ft/lbs difference at 950yds. I also used 110 deg and the 308 increased to 236ft/lb spread. I then tried 20 degrees temp and the lines came within 140 ft/lbs.

These calculations are from QuickTarget and therefore I do not know how accurate they are. Just thought it would be interesting to see on a graph.



Purple line = 6mm ARC velocity - 2600fps starting velocity
Red line = 308Win velocity - 2500fps starting velocity

Blue line = 308Win ft/lbs
Light blue line = 6mm ARC ft/lbs

[url=][/url]

That's interesting. Any chance you can throw in basic 6.5 Grendel Hornady 123 gr to compare?

[Zeneffect]

the precise reason i asked how to run the overlays. what speed on the 123? im looking at 2700fps because my gun.

[Zeneffect]

general mock up without all the altitude corrections. common velocity for 123's

[jasper2408]

general mock up without all the altitude corrections. common velocity for 123's

Man I need to start bugging the dev on letting us change the colors of the lines in the QT graphs. My old eyes can't hardly track that light blue line.

Nice comparison though. Closer than I thought they would be.

[Zeneffect]

Maybe it might be helpful if I post process the colors in photoshop to inverted or something. If you have 2, reference... nope nope nope. Can't do it.

[Phred]

What a bunch of salesmen.

With all due respect, they're speaking so vaguely as for it to be meaningless. Let me understand, terminal ballistics at range (which he will not identify), a 105-ish grain 6mm starting at 2650 is going to exceed a 175 SMK 7.62 starting at 2500-ish (20" barrel)?

Let's run the numbers:
6ARC subsonic at 1050 w/274 lb-ft
7.62x51 subsonic at 950yds w/491 lb-ft

If you want to say it stays supersonic longer, then say that. If you want to say it's effective at longer ranges, than say that. But don't expect me to believe that 274 is more/better than 491. Don't expect me to believe that terminal performance is better, unless you mean beyond the range the 7.62 can hit. That would be better external ballistics, wouldn't it?

LOL Hornady wouldn't do that or take claim to someone else's design would they? Whitley has been making these things since 2006.

[Fess]

But, but.... the shoulder is pushed back 0.03 inches (trust me, you can't really tell just by looking at it, though), so it is not at all like the 6mmAR