I just received my 16" WOA 6.8 KG coated black from White Oak. It is a Pac-Nor blank and I chose non M4 feedramps for this barrel. My question is there is a dimple underneath the gas hole on bottom of barrel. I know it is for some sort of gas block, but I was wondering if anyone knows which brand in particular? I believe any will work but if it is designed for 1 in particular I would like to get that brand. I am leaning towards Larue low profile and a 12" Larue. It is a mid length gas design. I must say I am impressed with the quality of this barrel. Anyone out there know what block the dimple is for?

ETA: I just checked and the dimple is very slight and is directly opposite the gas hole.

I have the dimple on my WOA SPR barrel and it aligns perfectly with one of the two set screws in the bottom of my Vltor gas block.

I would like to think the set screw pattern on my Vltor is standard and hopefully any quality set-screw gas block from PRI or LaRue would fit fine.

Good luck and let us know if this is true

So far all the different set screw gas blocks I have used has had the rear set screw in the same palce as it is installed in the same place that the port is drilled that leads from the barrel to the gas tube.

Awesome. Thanks and I will post my results with the larue or other block I use. I appreciate the quick answers.

Mike