Yes this will fit your magpul handguard. - Dark Storm Industries Delta Round Ring Hand Guard Cap

Had to get this for my Magpul hand guard. My rifle had the triangle cap from the factory. The finish is nice. The fitment is really good. No wobble when installed. Just make sure you have all the tools to take your gas block, or sight post off. That will need to come off to take the old cap off and put this on. My front sight/gas block used a hex key, but yours may be pinned on. So check that out first!