The M40 rifle has evolved over time, and Dan Ross with D.D. Ross Company has provided a special lugged optic platform created just for the M40A3, and it continued to be used in the M40A5. This scope mount features a larger Picatinny rail connected to the Remington action with #8-40 screws. Dan Ross worked with the Marine Corps to design the M40A3, and his top metal and bottom metal became part of the original contract. During the M40A5 contract, Badger SA scope rail was also used, but was a direct copy of the DD Ross top metal.
Using the 7.62 NATO cartridge, Marine Scout and MARSOC snipers using the older wooden stock M40 and Redfin scopes were not able to get the travel on the elevation needed for longer shots. The 7.62 was limited to around 700 yards, with older equipment. Dan Ross added 30 MOA to the scope base to allow for shots to 1,000 yards without improvisations that limited the ability to quickly transition to second shot kills.
The USMC Scope Mount from DD Ross features the USMC clip slot recoil lug pattern, and is machined from ordnance grade steel and phosphate finished.