TF2 takes place in the 1960s. Both of those guns were designed after the 60s.
Think of this.
Texans with Robot Hands building Giant Turrets shooting 50 Caliber Cartridges, with teleporting devices, ammo and health dispensers that provide perpetual resources, French people with cloaking devices, devices that fake your own death, 8 feet Russian Men holding gigantic Miniguns the average man can't carry, Boston teenagers with Radioactive soda and milk, a Double Barreled Shotgun that propels you upward when shot downward, Germans with healing devices that will never be created, saws that increase your rape meter with every hit, and an awesome Australian man who is the 6th richest person in America who makes weapons with unreal capabilities and eats breakfast steaks, and yells "SAXTON HAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAALE" while jumping from helicopters.
Yeah. All of this stuff was designed after the 1960s.