I'd like to build up a .308 AR battle rifle.  I want a reliable setup for hard use with a chrome lined barrel.  I am looking for combat accuracy not .5 MOA accuracy so something that maintain a 2 MOA or better out to 600 yards will be good enough.

My question is which .308 platform is considered the most reliable and will work best for the purpose I noted above?

Any thoughts on the Aero M5?

What barrels would you recommend?

Thanks!

The KAC M110 and LMT L129A1 have both been selected by major military forces and used in combat.

Hard to argue against those....


If on a limited budget Armalite has been used in limited number by a Canada, a couple of South American countries and Israel.

LMT MWS has an excellent reputation for reliability.  Wish I still had mine.

nvm

In for the education.
How is the new dpms Gll rated?

I have no doubt those are excellent choices if buying a factory built .308 AR but I want to build one.  

The upper and lower receivers from any of our commonly discussed manufacturers are more than good enough for what you want.

Likewise, there are too many good barrel makers to discuss each one.

Where you're going to have the make the more difficult choices is your BCG and your trigger.
I went with the Timney due to the heavier strike of it's hammer (that's the AR10 drop in model.....fits all AR 308 configurations as far as I know).

Then, after you assemble it, you need to put about 1,000 rounds through it over a 1 week period. You'll find out right away what doesn't work, and then you can replace it.

It won't be the upper or lower receivers that you replace. It will be smaller things like the buffer weight, or the mag release, parts of the BCG, etc.
1,000 rounds over a short period of time will rattle anything loose that isn't perfect.

G.

The most battle proven design is the M1A and the FAL.

The LMT and SR25 are DMR type rifles and shouldn't be considered "battle rifles". The design is not intended for kicking down doors and clearing rooms.

If you're wanting a 308AR to serve as a battle rifle, leave the bells and whistles behind and opt for a KISS setup. No adjustable gas blocks, full weight bcg, full weight buffer system, CMV chrome lined barrel,  standard flash hider, and learn to shoot it. Don't rely on gimmicks or extra parts to fix your shooting.

A battle rifle is only as good as the one holding it.

I have a Rock River LAR-8 that has been very accurate and exceptionally reliable.

My LAR-8 has thousands of rounds through it and still accurate and no problems.

For a build, I went with the AP M5 receivers. I think it's all about using quality parts and getting the gas setting adjusted correctly. I'd also recommend getting a Bolt and barrel from the same manufacturer.

I would also recommend moving this topic to the build it yourself forum, or you will get a lot more people posting factory options.

My requirements were very similar to yours. I wanted the rifle with empty magazine to be <10 lbs and I wanted to be able to sling up tight and not change POI.

My experiences with the Armalite AR10B A4:

Light Strikes with Mil Surp ammo: Removed firing pin spring. No further problems and no slam fires in well over 1000 rds.
Gas Key understaked: Allen screws could be backed out with one finger. I "field staked" them.
Over gassed: Once the rifle gets warmed up, every 3rd round or so suffers anemic ejection. I had my wife video the ejection port while I shot 20 rds. The casings are just barely clearing the port when the bolt ends it's rearward travel and begins to travel fwd. When the casing clears the port = good ejection, when the casing does not and the bolt begins its fwd travel = poor ejection. Malfunctions associated with this occur ~1:125 to ~1:200. They are always either stovepipes or spent casing backwards in the action above a properly chambered rd. I have an adjustable gas block coming to solve this. Took me years to finally get around to ordering one. I really wanted the SLR but waited too long and they stopped producing the railed version. Settled for a J&P. We'll see what this does for me. A heavy buffer would probably solve the problem but they are... heavy.

I have never been a fan of clamp on FSBs. Once I get the adjustable set up I may drill and tap it and dimple the journal underneath to give it something besides friction to keep it in position.

Other mods to meet my requirements. MI keymod free float tube and Armailte abbreviated "carryhandle A2" style rear sight.

The good:
Accurate especially for a chrome lined barrel. With good ball ammo, XM80, MAL 5-82, the rifle is effective on a man sized target out to 500 yds.
Trigger is great. Still a combat trigger just crisper.
Feed reliability: I have 11 gen 2 mags. They all feed perfectly. I heard recently from learned member of this forum that the original "waffle" mags were considered a shortcoming in the AR-10 being apt to split if a soldier in a chest rig dropped into prone too indelicately. Gen 2 "B" mags are sturdy and just always work.

Look for the barrel first.  This thread made me curious about the current selection of chrome-lined options, and they seem limited.  Fulton Armory sells an 18" chrome-lined Criterion barrel that would be suitable for your build.  LINK.  Criterion makes good chrome-lined barrels.

The Fulton barrel is intended "For use on DPMS/Remington/FA pattern .308 AR rifles with a rifle-length gas system", so I'd go with DPMS pattern parts.  (You can use a DPMS pattern barrel with an Armalite type upper, but it complicates the build.*)  If you use high quality components and assemble them correctly, you should get good reliability.  I agree with the poster above who suggested keeping it simple.  Use a standard bolt carrier group and a non-adjustable gas block.  I'd use a rifle-length receiver extension and standard weight operating spring and buffer to start.  If you want a collapsible stock, look at VLTOR's receiver extension.   If you are using this for a DPMS style rifle, you'll need to call DPMS for the correct parts needed.

I built a 7.62x51 AR around a 20" Lilja barrel and an Armalite receiver set a few years ago.  I haven't really shot it enough to trust my life to it (between 1,000 and 2,000 rounds so far).  However, aside from a couple hiccups during the initial break-in period, it's been 100%.  There are good assembly resources here, and I also like the This Book.  I also found THIS PAGE helpful, but it now includes the following disclaimer: "Update: As we head in to 2012 there are simply too many brands and variations to list on this page. While i will use it for the most basic of questions I suggest visiting the forum for up to date information."

* "You must use a properly headspaced bolt that matches the barrel extension type. This means you need to use an Armalite Bolt in an Armalite Barrel Extension and likewise for DPMS." (from the last link, above.)

Maybe just my ignorance but why not a melonited barrel? I chose chrome because I was unaware of the melonite option in 2011.

Armalite A4 CL barrel:

Link

That's my preferance as well.

OP... Give the PWS Mk216Mod1 a hard look.  Mine is dead-bang reliable and easily capable of man sized targets beyond 500 meters.

Your biggest considerations are going to be:

* Chamber dimensions
* Gas port location and diameter
* Correct gas tube length
* Correct dims on the BCG
* Correct buffer weight and length
* Correct spring weight and length
* Quality mags that will orient the cartridges correctly with whatever receiver choice you make
* Hand-fitting the critical parts to ensure smooth feeding, extraction, ejection, and bolt hold open

There are top-end manufacturers who have been chasing this demon for decades, who have engineering teams and large R&D budgets, and very few of them have been able to produce a reliable rifle.

Those companies are:

KAC with the newer RLGS 16" carbines, not the older versions.
LMT
ArmaLite Inc.

There are substantial differences in the gas systems and BCG's on the KAC, LMT, and ArmaLite guns, that are generally not available to the consumer.  The ArmaLite is the easiest to access component-wise, but is cheaper to just buy a DEF10 and drive on with the furniture that you want.  You will not be able to touch the price point from a build perspective.

I believe this man knows what he is speaking of. If the OP doesn't already know, we should mention that a .308 or large frame AR build is not as simple as an AR 15 build. I can vouch for the "hand fitting" part of the equation. I had to ream out a poorly drilled hole in my reciever, file down the mag catch, and polish the chamber to get parts to fit correctly... And I think it is still significantly over gassed, so I'm probably going to have to switch to an adjustable gas block... Which, had I done my research fully, I would have known that is where many/most end up after having similar issues. None of that is a big deal to someone mechanically inclined, or experienced working on small arms or in shops.

If you haven't assembled AR 15s, or worked in a machine shop, a .308 build probably isn't the place to start learning alone and unafraid. I'm not trying to discourage, just advise. Another route is to have an experienced friend on hand to assist, or just build both.

M5 set is fine. Use a lightweight barrel like the Faxon or juggernaught. Use a lightweight recoil system with adjustable gas block. I think you will not have any issues if assembled and tuned correctly.

That said, I have an lmt, a kac and an lwrc in 308. I think factory is always preferable from a reliability standpoint.

Jim Sullivan said the original AR10 from the 1950's was never as reliable as the AR15 for some reason.

I prefer to stay away from adjustable gas because things can walk around on you, and port erosion is exacerbated.

There's a reason why KAC went to a RLGS on the 16" guns, with a sealed gas system. They also have done a lot of work on the BCG to optimize the venting, coefficient of friction on the carrier rails that ride the upper receiver raceway, and use an extended extension tube (like ArmaLite did with the AR10 carbine from the start), with a different buffer.

LMT uses a hydraulic press to press-fit their gas blocks on the MWS, with a totally different gas port angle of 45 degrees, nuances to the BCG, straight gas tube that is aligned well, and pays attention to gas vent angles and locations on the BCG.

As a DIY builder, you would have to fabricate these parts from scratch, or score them from KAC, LMT, or ArmaLite Inc., and duplicate their assembly methods somehow.

The easiest route is to get the core ArmaLite operating system, to include their barrel, their BCG, their gas tube, their receivers, their LPK, their extension tube, buffer, ejection port cover assembly, FA, and put the furniture on of your choice.

It will be cheaper to buy a DEF10 and add the furniture of your choice.