both are nasty systems..the M-16 1/2 tracks and twin Bofors really tore into Chinese mass attacks. Tremendous firepower but you have to have a seperate ammo vehicle (0r two) for both just to keep the hungry guns spitting. I'm fortunate in that I got there too late for those initial mass attacks but we were always prepared. I carried 9 spare cal 50 barrels on my tank....I can only guess what the exchage rate was on quad 50s. M-19 and 42s carried 4 spare barrels, but they shoot out fast. Do not believe the 40mms had VT fuses and only impact detonation, so I can see the drawback in heavy vegetation. Thanks for posting the book info.