I often recommend Dytac aluminium outer barrels. They are not the best quality outer barrels on the market, but the weight saving is phenomenal. However, while recommending Dytac, I also give another piece of advice; conveyed to me by people I hold as experts.
It concerns the shonky grub screw which Dytac has purposed to locate the outer barrel into the upper receiver, to prevent rotation of the barrel when the barrel nut is tightened. Except, the grub screw is too narrow, so it often doesn’t do the job it’s supposed to. The barrel thus rotates marginally as it’s tightened. When the hop is inserted into the outer barrel, it’s located off twelve o’clock and the gun misfeeds.
I think this is good intel, which is why I always qualify my advice with it. However, I’ve never done it myself – so unless the person I’m speaking to has wisely elected to get their Dytac barrel fitted by an expert service provider, they need to figure out what to do.
Tackleberry isn’t known for sharing his techniques, but this time he’s been a bit loose lipped 😀