I'm guessing the M40a3 is the same thing as the M24a3 and one is the Army designation and the other is the Marine designation? You can find the M24a3 on one of Remington's websites (and maybe the M40a3?), and it is chambered in .338 Lapua. If you find one please post the price. I'm guessing around $6,000 but that is just a guess?