AR 556 or 308?

[U8395279]

Well... Its not about intelligence or skill, Its about a lack of information.

Not all bolt carriers within a platform will work with all uppers. Some SR25 platform rifles will work with LAR308 buffers, My Aero rifles had the carriers crash into the lower at the receiver extension boss using LAR308 carbine buffers and Tubb's flat springs. You had to stack a bucks worth of quarters in the tube to keep it from crashing. I eventually went to Spikes heavy buffers. The Aero lowers work better with a AR10B mag catch because its a tenth of a inch longer. Not all charging handles will work with all uppers. Not all bolt catches work in all lowers. Its not like the 5.56 guns where there is a specification and stuff just works. Its not rocket science but you cant just buy a pile of parts you like and slap them together like you can a 5.56 gun and expect it to be bulletproof out of the gate.

If you are talking about bolting on a new grip, dropping in a trigger yes, you don't have much to be worried about, But you can get into trouble with stocks because of different length receiver extensions/buffer requirements. Rails/forends are another thing. There are different offsets, different patterns. What works on a Mega upper might not work on a DPMS upper.

Well, but I am assuming that the person will use their skills and intelligence to do the necessary homework.

My 308 AR is sort of a Frankenrifle. While I certainly did not build it from scratch as the OP here is proposing to do ( I really don't have either the skills or the proper tools to do that ), the upper and lower are different brands, and I also have a third party handguard installed. Yes, you do have to be careful regarding the stock, and having an appropriate buffer and spring.

But I did not find it to be rocket science at all either. You just have to do some additional homework to insure compatibility. It is certainly not a good reason to avoid owning a 308 AR, in my opinion.

In my opinion, the main drawback to owning a 308 AR is the higher cost. Plus the fact that they are also typically heavier rifles.

But the 308 AR platform definitely has some advantages when it comes to being able to support cartridges like 308 Win, 7mm-08, 243 Win, and 6.5mm Creedmoor.


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[Koda]

It is definitely more of a "cult" caliber but that is why you do most of your blasting with 223/556 and use the 6.5 when is come time to reach out touch with a some put down power.

so if I understand AR's correctly you just swap out the upper build to swap calibers? The bolt and barrel complete the upper?

a quick web search shows Federal doesn't sell the Grendel but Hornandy does so its definitely not super popular. I'd be nice to see some other major manufacturers supporting it. I really don't want to build a complete upper in a caliber that will drift off to handloaders only.

 

[Koda]

Well, but I am assuming that the person will use their skills and intelligence to do the necessary homework.

that would be me. Admit I've never built one before but I've done my share of DIY projects and am even considering an 80% lower.

 

[Boboclown]

that would be me. Admit I've never built one before but I've done my share of DIY projects and am even considering an 80% lower.

Buy two or three in case you mess up the first time.

 

[U8395279]

But you do the majority of your shooting with the much cheaper 223/556 and switch to 6.5 as need be.

Well, but that then means having two uppers.

 

[Koda]

I don't mind having two uppers.

...of course that means at some point I'd probably get another lower.

so this is how these things multiply.

some good tips in this thread thanks everyone, really helped me out understanding the options.

 

[U8395279]

I don't mind having two uppers.

...of course that means at some point I'd probably get another lower.

Why buy another lower? It only takes a moment to swap out uppers.

If you are considering multiple uppers, you could also consider the 25-45 Sharps, which is .257 caliber, instead of the .264 caliber of the 6.5 Grendel. It is more compatible than the Grendel is.

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[Koda]

Why buy another lower?

they sit in the safe better that way seriously though if Im at the point of having two uppers the cost of another lower wont bother me.
this is a long term project for me but I figure Id start with a 100% lower and learn to build it and then buy a complete upper (or learn to build that too?). If I find it easy enough I'll learn to build 80% lowers because the garage machining part is well within my ability.

thanks for the tip on the 25-45 Sharps, I like options. I will consider it too if ammo is available easy enough.

 

[Brutus57]

Get an M1A if you want .308 and be done with it. Plenty of bells and whistles to personalize/customize or just stay with a very good rifle. I like the DPMS Gen II AR 308 but I don't need another caliber!

Brutus Out

 

[mrblond]

Those are nice! I like my

 

[Doc In UPlace]

Mine is stock...so far...

View attachment 273369

Someday I might Sage stock it.

Good thing that rifle doesn't have a pistol grip or a "shoulder thing that goes up", or it just might be dangerous. Bad enuf to have the deadly bayonet lug fer chrissakes.

 

[Boboclown]

Well, if you do get a 5.56 and use the stripper clips, let us know when you get "initiated" by one.

 

[U8395279]

they sit in the safe better that way seriously though if Im at the point of having two uppers the cost of another lower wont bother me.
this is a long term project for me but I figure Id start with a 100% lower and learn to build it and then buy a complete upper (or learn to build that too?). If I find it easy enough I'll learn to build 80% lowers because the garage machining part is well within my ability.

thanks for the tip on the 25-45 Sharps, I like options. I will consider it too if ammo is available easy enough.

But do you have a good workbench and all of the necessary tools? Putting together an upper from parts seems way more difficult to me than building a lower. I felt it was too much work myself, so I bought a complete upper assembly for my 308 AR.

And for my AR-15, I simply bought a complete S&W M&P 15. And then just did a bunch of easy things myself to customize and enhance the lower. Since I don't have the necessary tools, I had to get help in making mods to the upper.

Federal makes the 25-45 ammo. They have only two factory loads, though. A tough 87 grain Speer Hot Cor Spitzer for big game, and a Sierra 70 gr BlitzKing for Coyotes and other varmints.

In that last video I posted, they show a Coyote being shot though the shoulders with the 87 gr Speer Hot Cor. The 70 gr varmint load was not yet on the market then. You will see the Coyote drop instantly when hit. Then when the hunter flips the Coyote over, you will see a huge exit wound out the far side shoulder.

Really too tough a bullet for varmints, but people are reporting good results with it on both deer and wild hogs. There is a Facebook group dedicated to the cartridge, where people are sharing lots of good load info.

It is simply the 223 necked up to .257 The only different part needed is a different barrel. All other parts can remain standard stock AR-15 parts.

This photo from the review on AR15Hunter.com shows a good comparision:



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[eldbillbo]

If I was to buy an AR rifle I would have more use out of a 308 than a 556 as I could consider deer and elk hunting with it. Im confident in the reliability and build options and accessories for the 556 but dont really know much about the same in 308. Ive heard that finding reliable 308 mags can be an issue?

What are any drawbacks to an AR in 308?

Where did you hear mags were not reliable ? I suppose it depends on the model or rifle the early DPMS had some minor mag issues with factory mags but send them back a bad mag they send you a working one. I have never had mag problems I used the DPMS and the Magpul mags. Hunting Elke with a 6.5 grendle although a fine deer rifle would be foolish. but a .308 is well suited.

the only issue I had with the LR308 is not to shoot with the ejection port cover closed as this is ok with Ar15s as they are designed to open as the carrier goes back the .308 goes back too fast so the spent case gets stuck at least with mine and others a few others I have read. the fixed this problem with the G2

The biggest draw back is weight but DPMS as well as at least one other being Colt came up with a shorter lighter one known as the G2 . funny thing is I dreamed up this ideal a long time ago as I just did not see the reason for such a long bolt carrier making the receiver so long and making it feel a tad heavier putting the weight so far out . shortening the receiver and bolt carrier not only cuts out a few ounces with does not seem like much except when having its weight on your shoulder all day hiking or while aiming

The G2 is far more ergonomic and fits like a Ar15 .

I don't own one I was waiting for stag to come out with their Left handed .308 and hoping they go for the G2 style with is I use the Lr308 and its a lot more fun to shoot (but more expensive to shoot).

I still used a .300wm for elk but thats because I prefer to use heavy bullets and once shot one kill belief of having the right too for the job but the .308 will do the job as well and be easier to going through thick brush and harsh condition than a long arsed barreled fudd rifle.

 

[U8395279]

The biggest draw back is weight but DPMS as well as at least one other being Colt came up with a shorter lighter one known as the G2 .

Smith & Wesson's M&P 10 308 AR is quite lightweight too. Although its design is more proprietary than others. No way that one could get the parts to build it yourself.

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[IronMonster]

<broken link removed>

I really like my Aero rifles.

 

[Joe13]

Go with a 5.56.

If your going to go hunting, buy a bolt action hunting rifle (or lever) in .308 or 30-06 IMO. Tons of them used.

 

[eldbillbo]

Smith & Wesson's M&P 10 308 AR is quite lightweight too. Although its design is more proprietary than others. No way that one could get the parts to build it yourself.

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But it does not have the shorter receivers and bolt carrier group like the DPMS G2. Which makes it feel lighter as well because it moves the the center of balance back even though its only about a inch if you are ever able hold and aim with the 2 different styles you will feel it right away .

see how short it is in the back end like a Ar15 that little difference in length makes a big difference it feel.




It even looks more like a Ar15 except the longer mag well which is just something that can't be changed

 

[mjbskwim]

sounds more like the only drawback is the standardization of parts and accessories!

Yeah that's a "draw back" when you put AR into the equation but how many of your other rifles of different brands have interchangeable parts?
I built a few ARs and they are fairly easy,but I didn't go to the 308 to build cause I didn't really want to hunt for the parts that would fit my particular build.
So I bought the SR762. I went with the 308 because I just like the larger caliber better than the 22LR magnum JK. And although i had fun building i never seemed to like them enough to keep any. I have a few boxes of 308 laying around and like that caliber better so it was the 308 AR for me.
We have lots of 6.5 shooters around here. Both Grendal and Creedmore.Well some other wildcats too. But it's easy to find a place to shoot a mile here also,and longer range calibers are popular.
Reloading is the way to go with any caliber you shoot a lot of.And if i can do it anyone can
I don't know if anyone on here has done a 25 45 sharps yet but until you read that they are getting MOA accuracy with the guns,I would stay clear of that caliber.2.5-3 inches is the best I have seen on you tube.
Oh,you can do a 6.5 creedmore in the 308 platform.Not sure what it does that the grendal doesn't. 6.8spc is in that area also

 

[Pandaz3]

I have a couple of DPMS Pattern Aero Precision 308 builds and I have a store bought Armalite AR-10. You can't use Pmags in my Armalite, but many can, depends on if it is AR-10A or AR-10B, anyway mine is wrong for Pmags but I have a good number (10) of 20 round metal, 2 10 round metal and 2 25 round metal magazines from Armalite. The trigger on that Armalite is just a outstanding two stage trigger, I have a lot of AR triggers from names in the industry, none top the Armalite. Armalite has different pattern upper and lower receivers compared to the DPMS style pattern. Daniels Defense new version seems to be a Armalite pattern they are a top contender for quality. I have a good bit of M-14 experience including the M-14E2, which I qualified with, but that platform including the M1A only has nostalgia for me. AR 308s are inherently more accurate, and I was accurate with the 14.

All said if I were you I would buy a new Aero Precision, or buy all their Receiver parts including the pins and then you could buy the trigger, handguard, barrel, gas tube, gas block, Stock, buffer tube, buffer and spring, sights, muzzle device, pistol grip of your choice. either way it will be kind of expensive. go to AR15.com and download their how to build, get some punches from Brownells or Midway or Sears and go to it.

Great path and cheaper would be find a Ruger AR-556 for around $700. S&W makes a Sport version for a similar price point, but I like the Ruger. You then need Magazines and AMMO. Lots of AMMO, because they really are fun to shoot. When you get tired of the rachety trigger, research and replace it. You will notice more pleasure in your shooting. Nothing else is really needed.