Grendel Upper: Oversized or standard barrel extension tunnel

[Bonas]

Same here. I use my armorer’s receiver insert that I modified. It looks like a T shape with a shaft that fills the chart handle channel. I cut off some of the front section of the T handle so it could be used to punch out bedded barrels.

Last one I did tapped out with a hammer with much less force than I expected, very easy to do.

Was that upper bedded with Loctite 620?