Found this on the JP rifles website -
"JP Supermatch™ barrels in .308 Winchester/ 7.62x51 or .260 Remington are compatible with most AR-10 platforms except the Rock River LAR-8 or Bushmaster BAR-10. Due to the use of an FAL magazine, the extension piece on the barrels used in those rifles must be extensively modified to allow for feeding. Therefore, JP .308 and .260 barrels are not compatible with the RRA or BM rifles. However, our barrels may be modified to work with the LAR-8 or Bushmaster BAR-10 rifles."
Anyone know what modifications are required?