I have a PSA 308 that's on the heavy side for what I want it for, so I'm going to build a lighter weight rifle to replace it.

What does arfcom recommend for a lighter weight AR-10 m-lok handguard that still has a full pic rail on top?

FWIW, this will need to fit a DPMS "low-profile" spec upper if that makes a difference.

Thanks!

PSA makes them, SLR, Midwest Industries(I am waiting for them to get back in stock they are currently in production with MI)
From what I have read and the deep dive I have done on this the MI rail is going to match the PA-10 about the closest to the PSA rails that you can get.  Other brands even though they are DPMS low will have slight variations that does not match as well.  I am building a PA-10 from just receivers around a Criterion barrel right now just waiting on parts and the rail.

Just FYI there are a lot of little gotchas along the way with the PA-10 or any variant for that matter of AR-10, LR308, AR308, etc etc.  Since I am already on the PA-10 path I have done a lot of the research plus trial and error.  IM me if you have any questions or need details.  Also if you learn something new I would be interested to know because I am sure there is some stuff I just have not figured out yet.  
I currently have the PA-10 with a 16" upper PSA offers on a PA-10 Gen2 lower.  It has been really consistent on devouring literally anything I put in it.

For Standard pattern .308 AR’s, I  like Aero Precision, Ballistic Advantage, Zev HG’s. This will not net you a massive weight savings tho.

If you want a huge weight savings go with an SFAR or other SF 308 and swap out a full rail A.R. 15 size HG and BN.

I should have been more specific, I am not trying to match this new handguard to anything PSA.

I'm just saying that the PSA I have is too heavy so I'm building a new gun (probably from an 80% set) that will have a DPMS low profile upper, so I want a lightweight handguard to go with it.

I'm thinking of this one here.

https://80lowers.com/light-weight-dpms-type-ar-10-308-80-lower-receiver-set/

I asked them and they said that the set will be under 20 oz. (1.25 lbs) for 7075 which is on the light end for AR-10's AFAIK. Their spec sheet says 20 oz. but the engineer says they machine the lightening cutouts a little deeper than they used to, so it will be a bit under that.

That is a good looking set of receivers.

I stuck with the PA-10 just so I could swap lowers and uppers around and how not compatibility issues if I wanted to do that.  One lower has a PRS light stock and the other a UBR so I have options if I want something shorter or something more traditional for target shooting.

I like Aero and Midwest handguards, with the nod going to the former for my large-frame rifles.

I already talked to Aero (because that was one of my first choices) and unfortunately all of theirs are high-profile.

MI makes one specifically for low-profile receivers and it is in the running for sure.

I'm also considering one of these, which would be crazy expensive at about $400 all told, but it would weigh 8.5 oz. at 15" (including the barrel nut).

https://www.smokecomposites.com/hand-guards

I ordered that receiver set as a 100% machined set and am going with the Smoke Composites handguard.

I added it all up and with a standard BCG I'm going to be at about 6.5 lbs. Current PSA rifle is about 8 lbs. Not sure how much I'll really notice that difference but it'll be a pretty cool rifle in any case.

Might use a lightweight carrier, but I'm not sure how all that works in .308, so I'll have to do some research there.

Finished this build using the Smoke Composites handguard. The handguard is indeed very light and the rifle weighs right at 6.5 lbs as shown, which was the goal. I did have to use Brownell's titanium bolt carrier to get there though. It's sort of weird (in a good way) picking up an 18" 308 that weighs the same as some of my shorter 5.56 guns.

A couple of notes on the Smoke composites handguard:

The add-on "Picatinny" rail is made of very thin CF and is hollow/skeletonized and will even deflect a bit if pushed on from the top. It's not in-spec with any Picatinny rail AFAIK, and even though I ordered the low version to match the DPMS low pattern upper, the handguard top rail was still a hair shorter than the upper rail. I got the rail added on more for looks than to really attach anything to, which is good because it is too undersized both in height and width to be usable. Anything I tried to attach to it was loose, even if I tightened it all the way down. Worst is that the rail slots are way undersized. Anything with a lug which is made to fit into an actual picatinny handguard slot would not fit onto the rail.

The handguard is pictured as having almost a "camo" pattern in some of the pics on Smoke's website. This is a trick of lighting on the carbon fiber. They're just black.

I painted it using C series (air dry) Cerakote, because I was leery of heating up the carbon fiber. The people at SC said you could do it at 200-210 deg for a longer time than normal using the oven cure Cerakote, but I didn't want to risk it.

The handguard is about 2 1/8" OD which feels too fat to me. I should have paid more attention to that before I ordered.

If weight is basically your sole concern, and you won't need to attach anything to the top of the handguard then I very much endorse this product, but in the end, I'd say my overall feeling on it is "slightly disappointed".

I really like the receiver set from 80lowers.com. I got it in 7075 which they state on their site would add 2-4 weeks but mine shipped out in a few days. The Strike Industries dust cover I used was binding on something in the upper which required me to remove a little material to get it to work properly. I suspect that if you use a standard metal dust cover this would not be an issue. I opted to have the bolt catch roll pin hole threaded for a 6/32 threaded pin, and it's very mildly annoying that I had to order the pin elsewhere as 80lowers does not provide them. They were running a sale so I got the set for $378 which I think is a decent deal for a lightweight set that looks cool.

There was a little bit of wiggle in the upper/lower. I don't like that, but a .005 pivot pin shim from triggershims.com made it rock solid and I think this is a more elegant solution to this "problem" than something like an accu-wedge

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SLR makes lightweight handguards with a full pic rail, not inexpensive but super high quality…

Nice weapon.

How much does it weigh?

I got a better scale and it's 6 lbs 8.8 oz, so I actually just busted my 6.5 lb goal. Oh well, close enough. It's going to get about an oz. heavier because I just ordered a Roam magnesium handguard.

The Smoke composites handguard is just to fat around for my tastes. It'll be going on the EE at a hefty discount, FYI.

So here's the final version. 6 lbs 9.7 oz. so just little heavier than my goal of 6.5 lb.

Wish I'd known about the Roam handguards sooner. Nothing inherently wrong with the Smoke Composites one, but this is definitely more what I was looking for.

Attached File