I have heard some pretty ridiculous things about the .408, such as CheyTac making comments along the lines of "We build great rifles, but NO ONE can match our bullets". Sadly I have no experience with this rifle.
305gr-3500 ft/s 8295 ft lbs
419gr-3000 ft/s 8373 ft lbs
Never mind letter bombs. You would rather poison the drinking points than use the 419gr .408, it would do less damage.