GrendelHunter.com Handguard Clearance Problem

[MuddyFork]

First this is not a 'bashing post' about the guys at GrendelHunter.com or their produces, this is just to make you aware of what I found with my setup. I bought a 20" Ballistic Advantage Grendel barrel, Superlative Arms 750" Adjustable Gas Block - Bleed Off - Solid (set screws), and the 17" Grendel Hunter MLok Handguard. This setup will not work, because the bottom of the handguard completely touches this gas block. It looks like this handguard is not centered with the barrel, because there is plenty of space above the gas block. If you look at the photos of their guns you can see the barrels set lower in their handguards compared to other manufactures.

I have put both my 15" Midwest Industries and 15" Diamondhead USA handguards on this upper. Both of these handguards have plenty of clearance on the top and bottom, and they are no bigger than this Grendel Hunter handguard.

Parts List

http://ballisticadvantage.com/20-inch-65-grendel-dmr-fluted-midlength-ss-premium-barrel.html

https://suparms.com/products/750-adjustable-low-pro-solid-gas-block-melonite-finish

https://www.grendelhunter.com/product/17-grendel-hunter-handguard-mlok/

I returned the handguard and they gave me a partial refund. I had to pay shipping both ways, which I'm not really happy about.

Thank you everybody for the help I've found here.

[Lastrites]

Did you happen to ask what gb that they recommend to clear their rail?

[MuddyFork]

GH.png

[MuddyFork]

Did you happen to ask what gb that they recommend to clear their rail?

They said it was made to use their low profile gas block.

[mdewitt71]

I have their upper and handguard.... really liking it.
Give Andy a email or message on Facebook, he will answer all questions and help you out to ensure you know exactly what you are getting.

[mateba]

I have this gas block but mine is a clamp-on style. From what I understand, you need at least 1-5/8" internal diameter to clear the physical dimension on the gas block not counting for barrel whip. I used an ALG EMR-V2, perfect fit. Most new super thin handguards will not accommodate that gas block. Good luck. That gas block with a mid length gas system and trying to mount MLOK is a no go. Hope you don't need a vertical grip.

[LRRPF52]

Clamp-on gas blocks are the biggest culprits in not clearing the ID of a low profile, slim handguard.

[MuddyFork]

[grayfox]

?Handguard design. The ones I use (most are MI but I do have one GH total upper) all have an octagon shape so the bottom "flat" is narrow enough and lowered enough to clear the GB base (each flat around the circumference is pretty much the same size, like a stop-sign)... this one you have, looks like it has a wider, flattened base that sort of cuts off some of the freedom in the lower part of the guard. Hard to tell however from the website's pictures, is that wider, flatter bottom the part that's causing you the problems?
If so, no cure other than use a different, more rounded, equal-octagon-sides-style HG profile.

[Sticks]

I do like the looks of them. If I really wanted it to work, a little machining around the GB would go nicely.

[MuddyFork]

I do like the looks of them. If I really wanted it to work, a little machining around the GB would go nicely.

[grayfox]

On the left, a GrendelHunter upper complete assembly, their own GH HG, 0.740" dia 18" barrel at the mouth of the HG.
On the right, Faxon group buy with Troy Battle-ready M-Lok free float HG, 0.700" dia 18" barrel at the mouth of the HG.
The GH measures 0.600 from centerline of the barrel to the bottom flat (inner surface) of the HG.
The Troy measures 0.750" from centerline of the barrel to the bottom/inside of the HG flat.

From what I can see the barrels in both are centered.


20180224_101322.jpg

[MuddyFork]

greyfox, It looks like your Grendel Hunter handguard is a different design then the one I bought, and the ones show on their web site.

[grayfox]

Right, that's what I was saying. The one I have, although it is a smaller diameter than my Troy/Midwest Industries, is a regular shape "stop-sign" octagon, and centered on the barrel. So clearances in any direction are much the same... except for the extra space at the top, under the pic rail. The gas block top fits under there.
If I were you I'd get rid of the flat-bottom one that you have... maybe you can return it, or sell it. or chalk it up to lesson learned... that's just me, though.

I had a couple of non-functional HGs I bought, for one reason or another; one I was able to return but one I had to eat the cost... o well.
Now I stick to either Midwest or Troy and save me the headaches.

[MuddyFork]