The Even Bigger Barrett - XM109 (1990s)

Originally known as the Objective Sniper Weapon (OSW), the XM109 now bears the designation Anti-Material Payload Rifle (AMPR). Using the existing lower receiver from the M82/M107 rifle, Barrett built proprietary upper receiver and magazine to accommodate a much larger new cartridge. Utilizing a five-round box magazine, the Barrett XM109 would fire 25x59mm grenades in order to engage hard targets such as light armored vehicles.

What is known about this rifle, is that it packs quite a punch to the shooter’s shoulder. Even with the muzzle brake, the recoil force of the XM109 was over 60 foot-pounds, compared to the 36 foot-pounds generated by the M107. Ammunition itself, is another question, as weapons like the XM307 (that fired the same round) have since been canceled.

https://www.thefirearmblog.com/blog/2018/12/05/potd-barrett-xm109-ampr/