6mm ARC or ?

Josh06

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I'm putting together a new upper that I will use for deer out to 250. I was almost set on the 6mm ARC, but it looks like I could get almost the same performance from 6x45. I'm looking at 90 gr bullets and they seem to be almost even at 2700-2800 fps out of an AR. Does anybody have actual experience with either or both?
 

SteelBanger

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I'm also considering a 6 ARC build, but mostly for target / coyote shooting. I've looked at the 6x45 and I just don't see much upside over the ARC and if I understand them right it looks like the ARC will handle the longer / heavier bullets better than the 6x45? I guess the main appeal of the 6x45 is if you have a ton of 5.56 brass laying around that you could resize and use, but unless you just want to be different and go with the wildcat there are definitely perks to shooting a factory supported cartridge. But now you have me staring at my buckets of 5.56 brass debating back and forth again! lol
 

long450

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I have shot 5 deer and 40+ pigs with a 6mmAR (which is the same as far as performance). Used 70gr varmint up to 90 grain bullets. Barnes 85 grain ttsx, Hornady SST, Berger match 90 grain, and Nosler partitioned all worked for me. All deer were broadside lung shots and none went very far. They do not produce very big blood trails though.
Pigs were shot from every angle but most were shot just behind the ear and dropped .
The upside of the ARC over the 6x45 is commercial ammo is produced for it. Probably cant find any now though.
 

Hecouldgoalltheway

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I just threw together a 6mm arc, and although you can't find ammo now, the factory 108gr eldm are only about $22/box when people aren't trying to take advantage of each other. With that cheap ammo, my rifle is half minute capable in a 22" barrel where I get 2,720 at 68°F. I managed to buy 12 boxes when I first decided to make one. I can't imagine any reason to hand load for them when excellent factory ammo is so cheap
 

budlight

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Hecouldgoalltheway

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I decided on the ARC because of the powder capacity. I found a rifle + 2 inch gas system So you can do the full power bolt gun loading. I went with 24 inch and .750 gas block. It is kind of disappointing compared to a 243 win but I didn't want an AR-10.


Man, the weight to that ar10 jump just seems to be enough to keep me from hunting with them. I've had a half dozen different ar10 rifles over the years, including some very nice models, and even with a carbon fiber barrel, they are just freaking heavy. I always end up trading them. Carrying an ar hunting is already an inconvenience due to the noise they make, the fact that they hang up on everything, it's so hard to protect all of that paint, etc, so then when they weigh 20lbs with optic and bipod, I just stop reaching for them. I'm sure you'll love your 6mm arc. I love mine
 

Josh06

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Appreciate the replies. I was going to build this upper because I ended up with a stripped upper because I had to by a set to get a lower I needed (well, wanted lol) and had some parts laying around. I like the idea of a 6mm gas gun but never could get really excited about either round so ended up going 100% the opposite direction and decided to sell all that and put together a 22 creedmoor bolt gun with the money. Just dropped off the barreled action to get cerakoted this morning.
 

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Gunpowder

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I've had all these rounds mentioned except the 6 arc, but had the wildcat versions of it which the arc basically copies.

6x45, easy, cheap, accurate, was just uninspiring for some reason. Handles up to about 87 gr non tipped bullets pretty well.

243 lbc, very accurate, more expensive Grendel brass but not terrible. Weak bolts so buy a good one, don't cheap out as I broke cheap bolts, 2 of them with a round count of about 1400 rounds iirc. This was basically a 6 arc. I shot 87 vmax mostly at 2900 fps or so iirc with 8208.

243 wssm, very accurate, very tough brass, 87 vmax at 3200 from a 22" barrel. Proprietary parts other than the float tube so you'll have to have one built if you go this route. But it's a coyote hammer! Obvious reduction in barrel life from the others so it's not a daily driver. And mag capacity limit of 7 or 8 I think. Not a problem for me but worth mentioning.

243 win, I've had two, the first built 8 or 9 years ago on a regular 308 platform and used a cf float tube. Somewhat heavy and awkward, was accurate. Took it apart and sold off the parts.

Second 243 win I bought a year ago, dpms g2, one of the last ones I've seen for sale. Sweet, sweet rifle imo. If you're not familiar these are almost a cross between the 308 and 223 sized platforms. It carries like an ar15. Uses a bolt carrier about 1/2" longer than a 223, and smaller receivers than the old 308 stuff. Carbon fiber float tube and 20" barrel. My load with 87gr bthp and H4350 is 3070 fps so a big jump from the arc but noticeably less flat than the wssm. Most importantly though this rifle might be the most consistently accurate one I've ever had, with 200 yd 3 shot groups never over an inch, mostly about 3/4". And shot out to 700 it stays 1/2 moa. The best part is cdnn was selling dpms barrels for it in 243 and 260 for 80 bucks so I picked up a few. As long as I don't break one of the other parts I'm set for a long while.

As far as long vld type bullets, the wssm and 6x45 are out for sure. The 243 has a 9 twist so limits it somewhat, my wssm has an 8 twist but you run out of mag room way before you get to the 108 type bullets. So that really only leaves you the Arc if that's the bullets you want to run.
 

budlight

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Man, the weight to that ar10 jump just seems to be enough to keep me from hunting with them. I've had a half dozen different ar10 rifles over the years, including some very nice models, and even with a carbon fiber barrel, they are just freaking heavy. I always end up trading them. Carrying an ar hunting is already an inconvenience due to the noise they make, the fact that they hang up on everything, it's so hard to protect all of that paint, etc, so then when they weigh 20lbs with optic and bipod, I just stop reaching for them. I'm sure you'll love your 6mm arc. I love mine
I have two 24 inch stainless fluted in 308. When I was young and tough I didn't think anything about humping my M-14 anywhere with all my gear in the tropics. Now I use a quad to get me close. :)
 

CaptnC

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I know this is a couple months old but...

I have everything except the barrel for a 6mm ARC AR-15....had one on lay-a-way, but got a cancellation notice for the back order, so I have bullets, dies, brass...everything for the gun it's self, just no barrel!

I think I would like to have a 24"SS minimum would be 20"....I even have the 950 adjustable gas block for the barrel I thought I had coming!
 

Orange Dust

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I just went through all this. I ended up with a 6.8 ARP 3R barrel. Very happy with it. They are at least 100fps faster than a 6.8SPCII Barrel. Not real far behind a .270 Win in performance.
 

Hecouldgoalltheway

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I know this is a couple months old but...

I have everything except the barrel for a 6mm ARC AR-15....had one on lay-a-way, but got a cancellation notice for the back order, so I have bullets, dies, brass...everything for the gun it's self, just no barrel!

I think I would like to have a 24"SS minimum would be 20"....I even have the 950 adjustable gas block for the barrel I thought I had coming!
You can get a barrel from ER shaw. You'll have it in a month to 6 weeks, and it will impress you. Oh, and they are really reasonable.
 
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