What lower pattern would you go with?  I am thinking about building one and looking at the DPMS styled lower, which of the different AR10's are more prevalent in the real world?

If I were to do it all over again, I WOULDN'T ASSEMBLE.

I'd just spend the money & go with LMT, KAC or LaRue and be done with it, resting easy on a safe & secure warranty and enjoying the resale value instead of a mis-matched franken-gun bashed together runs right now but may not run in the future or accuracy can open up on it.

The tolerances are just too variable when even going with the SAME company for parts compatability.

A thousandth here and another there and whaddaya know you have a 3.0 MOA 'battle rifle'.

Then the headaches of gas systems, dwell & lock time issues, short stroking, not seating cartridges all the way into battery - ugh.  Not to mention buffer weights, spring tensions, triggers, mag, release fit, bolt release or lock open problems and the forward assist issues.

A factory gun is already sorted out, or has a warranty to GET sorted out if you get one that doesn't run.

Ever see the video of BCM sorting through parts they receive into GO & NO GO stacks?

HERE

And NO they aren't doing .308's...

There isn't much of a MILSPEC for .308 AR's and compatability issues.  Tight is good, but not TOO tight and not TOO sloppy.  

How many .308 AR parts will you get that are on the far side of the specs of the tolerance?  What are you going to do when they don't run well together?  Some company's won't take back their parts if they are within spec and used, but, a poor fit in YOUR assembly.

But that's just my personal experience from dealing with .308 AR's.

One M5 Aero (never-ever-ever-EVER again!  M5 "matched" upper & lower+BCG that is ONLY supposed to work with their FA - yeah NOPE and a Ranier Match Barrel)

Two Mega Matens (better, but its the OTHER products that gave the tolerance headaches, BCG-barrel-gas system interface)

I have a DPMS GII that is a shooter-rack grade rifle and am planning to purchase a KAC to stick in the gunsafe in case the elections go full she-NON-igunz.

In summary=  NO, I will not be assembling a .308 rifle ever again.  It just doesn't make fiscal or time sense to do it RIGHT.  

Your Mileage May Vary (YMMV)

Will

Why is that a big deal?

From my experience, when you commit to one lower/upper/BCG/LPK/UPK stick with that manufacturer. Pick the barrel,handguard, pistol grip and stock you want.

Interesting, thank you.

I agree with this, but am slightly less angry about it. If, you are like the OP, and do a little reading first, you will know that .308 ARs require more tinkering... Expensive tinkering. If you like to experiment and work on things, it might be fun for you.

If you want to easily slap together a gun that will work 100%... Buy factory.

Im just curious if you feel the same about ar 15s.

AR 15s are relatively easier to find and fit parts, and therefor much easier to make reliable.

One of the reasons I asked was because now I have built over a dozen AR-15 rifles and they are pretty easy and all of mine run with no problems at all, but have never ventured into the AR-10 and wanted to know the pitfalls in building one, they are indeed a different animal.

Thanks guys.

Somehow, I find it amusing to read what amounts to "don't do it yourself" in a DIY section of the forum. Then again, I have a twisted sense of humor.

Personally, I would say exactly the opposite, unless you want to relinquish yourself to being just an owner/operator. If you're a tinkerer, and want to tinker my advice is to stay as far away from proprietary hullabulloo as possible. That's coming from the proud owner of a Rock River LAR8, who has had to modify things to get them to work within a system that is so proprietary, it won't even function reliably with modern (polymer) versions of the magazines that it was designed to use (FN FAL). Try asking one of those proprietary companies like Knights or Rock River to provide you a barrel or a full upper chambered for something like Creedmoor, and see how far you get.

DPMS pattern is certainly the most common one out there. If you're looking to get the widest range of stuff available, go with that pattern. Armalite pattern (technically the only AR-10, since Armalite holds the property rights to the name and some specifics of the design) is a little less common, but the next most available. Personally, I think Armalite is more for purists who want the original. In all reality, you could survive on your own with either pattern. The DPMS is just more common.

Also, since I know where you live stop in and talk to Falkor Defense (formerly SI-Defense) on the north side on 89. I'm sure if you ask them, they would explain why they went with the DPMS pattern on their receivers. If you ask nice, you might even be able to walk out their door with a blemish discount.

SI(Falkor)  Interesting, I was just by there the other day, thanks for the tip.