Educate a noob on non 5.56 ARs

Coffee · Jul 29, 2014

So, we can buy lowers now! This got me thinking on what I'd want to build. I've decided I'm not interested in a pistol, a tax stamp, or an HBAR version of something I already have.

Before MSP "gave us permission" to buy lowers again, I had been considering a bolt action 308 for hunting. Now that lowers are green-lit, I'm thinking I might build an AR for hunting.

So what do I need to know? I've taken a look around the non 5.56 sticky, but have some extra questions:

-What's your preferred non 5.56 caliber, and why?

-How does 5.56 compare to 6.8 and 300blk (the two calibers I'm leaning toward) in terms of velocity, accuracy, ease of acquisition? Edit: How do these compare to 308? ie, if I want to hunt, would I be better off buying a 308?

-Do I understand correctly that non 5.56 ARs don't have to be HBAR/Pistol/SBR?

BradMacc82 · Jul 29, 2014

Coffee said:
-What's your preferred non 5.56 caliber, and why?

-How does 5.56 compare to 6.8 and 300blk (the two calibers I'm leaning toward) in terms of velocity, accuracy, ease of acquisition?

-Do I understand correctly that non 5.56 ARs don't have to be HBAR/Pistol/SBR?

Initially, it was 300BLK. And while it proved itself accurate, capable (deer-hunting), and available (before the ammo crunch really got going) - It wasn't long before the 2 300BLK uppers were sold off. I've since moved on to a diff't caliber.

Velocity wise, the 5.56 has 6.8 and 300BLK topped. Accuracy wise, every single one CAN be more accurate than the bag of meat behind the trigger is capable of being. 6.8 has 300BLK topped on velocity in supersonic loading. Either caliber (6.8 or 300BLK) can be found online, but ideally it's better to handload for either to keep the cost per round down.

As for the HBAR part, got no clue. Never bothered to build HBAR's since my lowers were pre-ban.

iH8DemLibz · Jul 29, 2014

If you really want it for hunting only, buy a 308 and be done with it.

It'll kill anything in North America.

photoracer · Jul 29, 2014

The only real advantage of 6.8mm over 5.56mm is that is it more leathal at longer ranges. That was the entire point of the design was to give the squad's best marksman the ability to kill at up to 800 yards without a redesign of the basic AR. And without the need to have a sniper in every squad with a bolt gun in .308. Unlike say the AR10 in the heat of battle you could swap a 5.56 upper and vice versa as long as you swapped the upper/BCG and the mags. 5.56= a varmint round, 6.8= a hunting round. There are a few other calibers you could also run. I have both 5.56 and 6.8 ARs. The fastest 6.8 and .308 rounds are about the same at about 2850 FPS. The .308 better Ballistic Coefficiant allows it to remain supersonic to a longer distance so it makes a better long range rifle. Berger supposedly makes a 140g 6.8 round that is supersonic to 1000 yards, which puts it very close to the 175g .308, but it requires the use of PRI mags which allow a longer OAL. Personally I have never been able to find any of these if they actually exists. The 6.8 is plenty lethal at 600 yards using Hornady 120g SST or 110g V-Max. SSA makes some great ammo of the 6.8 but as we all know the secret is to reload your own. If I really want to hit something at over 600 yards I would more likely grab my .308 bolt gun.

Pinecone · Jul 29, 2014

An advantage of .300 Blackout is that it uses the same mags and BCG as 5.56.

Since MD defines copy as interchangeable (not identical) parts, I would say that any caliber would have to be HBAR in a rifle. As you can swap a .300 or 6.8 barrel for the 5.56 barrel. At least, when I build mine, I will use a heavy barrel.

.300 Blackout shoots a 110 - 135 gr bullet in the low to mid 2000 fps range (I have been looking at 125 gr loads at 2150 fps).

BradMacc82 · Jul 29, 2014

Best I ever achieved was 2430fps with H110 and 110gr Hornady Vmax's. It wasn't a load that was easy on brass.

I'd argue that the 6.8 isn't a copycat as the bolt and magazines aren't interchangeable with a 5.56. My .50 Beowulf, same deal - diff't bolt and mags, but that's an HBAR by MD standards.

kmb · Jul 29, 2014

I sent straight to .308 in AR form. S&W AR-10 to be exact. Cost, reputation, and warranty were my key factors. Lots of nice .308s out there across many price points. I wish you the best. I wanted an LWRC (to support MD) but didn't have the $$ to spend. I also considered Noveske as they donated to a charity of mine. I sometimes wish I held out for the Colt 901 to come down from panic prices. I think 6.8 and 300BLK are good choices as well. Try to shoot them and see what you like. That's the best advice I think anyone can give. When I bought my .308 it was a call to FBI, cash, and have a nice day.

Robert1955 · Jul 29, 2014

I am planning on a 6.8 build for my next build out, and a 300 Blackout to be able to drop on to my 5.56 lower.

jimbobborg · Jul 29, 2014

photoracer said:
Berger supposedly makes a 140g 6.8 round that is supersonic to 1000 yards, which puts it very close to the 175g .308, but it requires the use of PRI mags which allow a longer OAL. Personally I have never been able to find any of these if they actually exists.

I have two of them :innocent0

If you want fast, 110gr hunting rounds you NEED SSA brass, preferably the older version. More room in the case. And a 1 in 11" or 12" twist rate barrel and the Spec 2 chamber. I've gotten 2700 fps with 110gr Accubonds and RL10X powder. The primer was flattened but no swipes. 2.300" COAL and the PRI mags are a wonderful combination with this caliber.

Pinecone · Jul 30, 2014

BradMacc82 said:
I'd argue that the 6.8 isn't a copycat as the bolt and magazines aren't interchangeable with a 5.56. My .50 Beowulf, same deal - diff't bolt and mags, but that's an HBAR by MD standards.

Copycat is the <29" or two of the "bad" features. Copy or imitation is when the parts are interchangeable.

You CAN swap the 6.8 bolt and magazines and barrel into a 5.56 and vice versa.

So, IMO, they are copies and need to be HBAR to be legal.

The term is INTERCHANGEABLE and not IDENTICAL.

fidelity · Jul 30, 2014

But if you exchange just one of the above items on to a functioning rifle with a 5.56 receiver, the rifle is NONFUNCTIONAL, correct? Play that logical argument out further.

erwos · Jul 30, 2014

OP, you are best off buying a .308. DPMS makes perfectly good rifles in that caliber at a very reasonable price point, and you can get steel-cased .308 for less than 50c a round shipped.

Pinecone · Jul 30, 2014

fidelity said:
But if you exchange just one of the above items on to a functioning rifle with a 5.56 receiver, the rifle is NONFUNCTIONAL, correct? Play that logical argument out further.

You can play that one out. I understand your argument. Are you willing to take the chance on Frosh agreeing with that?

I prefer to make SURE I stay out of the grasp of MSP and soon Frosh.

photoracer · Jul 30, 2014

jimbobborg said:
I have two of them

If you want fast, 110gr hunting rounds you NEED SSA brass, preferably the older version. More room in the case. And a 1 in 11" or 12" twist rate barrel and the Spec 2 chamber. I've gotten 2700 fps with 110gr Accubonds and RL10X powder. The primer was flattened but no swipes. 2.300" COAL and the PRI mags are a wonderful combination with this caliber.

You mean you have 2 of the Berger 140g rounds? Gee you are lucky. Currently I am using a PSA 20" A2 CMV CL 1:11 twist barrel that they had on a sweet discounted upper one night. Had some feeding issues to start with that I fixed by honing and polishing out the feed ramps. Shoots plenty accurately but I plan on replacing the barrel down the road with an 18" Wilson Combat Match barrel fluted in SS. Or maybe a Lothar Walther in their LW-50 SS. I bought it to build a DMR rifle, which I completed, but it is killer on groundhogs at long range using Hornady 110g V-Max. Also have some SSA 85g and some SSA 110g Sierra Pro Hunter. I think I have close to 7 varieties of 6.8 ammo. All seem to shoot decent. Around the farm at least I have not taken my .308 bolt gun out of the safe since I built the 6.8mm.

babalou · Jul 30, 2014

What about the 6.5 Grendel? Saw some site that said that was the better AR-15 round. Never shot it.

FlatsFlite · Jul 30, 2014

I have a 6.8 ARP and 6.5 Grendel. Tough call between the two. Nothings gets away within 500 yards. Both are 1/2" guns. But if I had to chose just one, the 6.8 for purely personal pref.

Coffee · Jul 30, 2014

let's say I went the 6.8 route. What manufacturers would you recommend for barrels or complete uppers?

BradMacc82 · Jul 30, 2014

Complete Uppers - Stag, Bison Armory, Wilson Combat, etc.

Barrels - pick a price point and go from there. I'd likely go W.C., if it were my money being spent.

jimbobborg · Jul 30, 2014

photoracer said:
You mean you have 2 of the Berger 140g rounds? Gee you are lucky. Currently I am using a PSA 20" A2 CMV CL 1:11 twist barrel that they had on a sweet discounted upper one night. Had some feeding issues to start with that I fixed by honing and polishing out the feed ramps. Shoots plenty accurately but I plan on replacing the barrel down the road with an 18" Wilson Combat Match barrel fluted in SS. Or maybe a Lothar Walther in their LW-50 SS. I bought it to build a DMR rifle, which I completed, but it is killer on groundhogs at long range using Hornady 110g V-Max. Also have some SSA 85g and some SSA 110g Sierra Pro Hunter. I think I have close to 7 varieties of 6.8 ammo. All seem to shoot decent. Around the farm at least I have not taken my .308 bolt gun out of the safe since I built the 6.8mm.

Since I bolded the magazine part, no. I'm currently using a Bison Armory 20" SPR upper I picked up for $550, including a Young's NM BCG. I need to take her out for deer this year.

jimbobborg · Jul 30, 2014

MidwayUSA is saying the bullets will be back in stock in September. I might have to snag some.

Educate a noob on non 5.56 ARs

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