Nick Atkinson of Team Crimson Trace was using a skeletonized AR lower at the FNH 3Gun Championships. It is a prototype and as you can see it is not fully finalized and coated.
According to the lower, it is stamped “AR15TARGETS INC.”
No other detail on this custom lower but NIck was able to finish the fastest on stage 8 of all the 3Gun shooters that day.. Perhaps the lighter lower helped.