6mm ARC Cartridge - Is this the end of the quest for AR-15 / M-16 perfection?

I just saw an article extolling the virtues of the 6mm ARC over other m-16/ AR-15 cartridge options.
It has a bullet weight of 108 grains which is better than the 55 gr of the original 5.56 and
a BCF of .520 for 1000 yard supersonic flight and lower wind drift. I did not see much on
the terminal ballistics of it. Will it punch through hard stuff or just fall apart? Will it tumble like the
original M193 ? I was thinking the 6.5 Creedmore or something similar would be chosen for an
slightly up-sized weapon system and we would get away from the AR gas system to a short stroke piston
style action. I personally like the 6.5 bullets in the 120 to 155 gr range at velocities that keep the recoil
comfortable.
What are your thoughts on this development?

Quote:

---

Originally Posted by SilverBear

What are your thoughts on this development?

---

Another nonsense round like 6.8 useless and 300 worthless. Seriously though, I don't even read up on these magic bean cartridges unless that gain traction for several years.

The utility of a .520 BC with 1000 yd supersonic flight is of dubious utility for a shoulder fired carbine whose role is to engage the enemy out to 300 yards. Typical engagements are much closer. You can give troops a laser beam and their ability to see and effectively engage is still about 300 yards. The direct impingement gas system is superior to the short stroke piston in a light shoulder fired rifle.

Quote:

---

Originally Posted by SilverBear

I just saw an article extolling the virtues of the 6mm ARC over other m-16/ AR-15 cartridge options.

I was thinking the 6.5 Creedmore or something similar would be chosen for an slightly up-sized weapon system...

What are your thoughts on this development?

---

Since you asked... My 2¢:

1. The ubiquitious .223/5.56 does everything 90% as well 90% of the time as any of these "new" AR-15 mag-length rounds, and it's so cheap and plentiful that there's no point considering anything else.


2. The 6.5 Creedmoor (Spelling counts!) is the same length as .308/7.62NATO, so you're not talking "slighly up-sized" but "AR-10."

My thoughts on the 6.5CM vs. .308/7.62 are the same as #1 and .223/5.56, above.


If I were regularly shooting past 600yds, then these exotic cartridges might be appealing. I'm not, and I'm better off with the standard NATO cartridges...

If you already have a precision AR chambered in 5.56/223Wylde or any of the various accurized variants, start loading 69&77 grain TMK’s. Good ammo will get you out pretty far.

I’m not sure what their altitude is but this guy gets out to 1500 yards with 77gr Berger’s at mag length.

https://youtu.be/sOumuAb1KEQ

Quote:

---

Originally Posted by Bimmer

Since you asked... My 2¢:

1. The ubiquitious .223/5.56 does everything 90% as well 90% of the time as any of these "new" AR-15 mag-length rounds, and it's so cheap and plentiful that there's no point considering anything else.


2. The 6.5 Creedmoor (Spelling counts!) is the same length as .308/7.62NATO, so you're not talking "slighly up-sized" but "AR-10."

My thoughts on the 6.5CM vs. .308/7.62 are the same as #1 and .223/5.56, above.


If I were regularly shooting past 600yds, then these exotic cartridges might be appealing. I'm not, and I'm better off with the standard NATO cartridges...

---

Wrong, wrong, wrong!

5.56 is 99% as good as the others, not 90%!

Quote:

---

Originally Posted by OdinIII

5.56 is 99% as good as the others, not 90%!

---

Well, I was trying to understate the case for 5.56/.223...


A couple examples of the 10% of extreme situations where 5.56 falls down:

1. I just read a review of Springfield's AR pistol with the 5.5" barrel, chambered in 5.56, and MVs are down in the 1,600fps range.

IMO, that's just a stupid choice of caliber... Better would be some kind of PCC, ideally chambered in 10mm, but maybe even 9mm, also making 1,500+ fps, but with bullets 2-3 times as heavy and with 2-3 times the frontal area.


2. If I were doing a lot of shooting past 500 or 600yds, then something flatter shooting than 5.56NATO (or 7.62NATO) would make sense.

The major advantage of a high BC bullet is not flat trajectory, because higher velocity can compensate for that, but it is the much better wind drift that is apparent even under 600 yards.
A high BC bullet will keep you in the kill zone while the other bullet goes a yard to the right or left. 9 inches of drift or 15 inches of drift, a range finder won't help you with that.
At 500 yards a 223 has 15 inches of drift while the 6.5 has only 9 in a 5mph crosswind.
Do you think that is important?

Quote:

---

Originally Posted by SilverBear

The major advantage of a high BC bullet is not flat trajectory, because higher velocity can compensate for that, but it is the much better wind drift that is apparent even under 600 yards.
A high BC bullet will keep you in the kill zone while the other bullet goes a yard to the right or left. 9 inches of drift or 15 inches of drift, a range finder won't help you with that.
At 500 yards a 223 has 15 inches of drift while the 6.5 has only 9 in a 5mph crosswind.
Do you think that is important?

---

To argue, for the sake of argument...

1. I don't anticipate trying to kill anything at 500yds...

Since 95-99% of my shooting is within 300yds, no, I do not think that reducing wind drift that much is important enough to adopt a new cartridge and buy a new rifle, new ammo, new magazines, etc...


2. .223 vs. 6.5 (Creedmoor?) is apples and oranges. One fits in a standard AR-15, the other requires an "AR-10" sized rifle, mags, etc.

It's designed to replace AR10 setups, not AR15 setups. That's the difference that keeps being overlooked.