Nice build. I really like the vxr firedot. It's the best of both worlds IMO. I use to have the santan lower and a Geissele rail but ended up ditching both. The santan wouldn't mate tight to anything, and that ambi on the support side was too floppy for my taste. Ended up switching the geiselle for a bcm. weight change was dramatic. Looks like you got a solid rig though! Show some groups!