Zel Custom has a new upper for the AR-10 and LR-308 platforms called the Spartan S3.  The Spartan S3 is a bolt action upper that allows an owner to shoot .50 BMG, .416 Barrett and .338 Lapua.  This upper is similar to other uppers by Zel Custom (and other manufacturers) that allow the shooting of heavy calibers from am AR-15 lower.

The Spartan S3 uppers can be had with either Mossberg or Lothar Walther barrels in lengths ranging from 18.5″ to 32″.  Pricing starts at $1,898 and goes up depending on options selected.

The upper shown in the photo above is unfinished, but various finishes are available including parkerizing, ferritic nitrocarburizing, and CeraKote.