Each Gun in MGS V: The Phantom Pain has the different timing to knock out the guards. The stuns and tranqs were inconsistent with what they have adapted in MGS Ground Zeroes. This Phantom Pain guide helps you know how long the tranquilizer and the stun gun works with different guns. Check the Below List for the approximate timings for the guns and combat style you use.
How long the Tranquilizers work
Testing Tranquilizers with different weapons regardless of item grade results in something like 'ZZZ'. The Pistols/SMGs, Rifles, Grenades and mines all last for 2.30 max. There is no list for the different duration as it is same will all the weapons in the game.
How long the Stuns work
The Listed below shared for different weapons have different duration in Minutes: Seconds
Note: Times may not be accurate to the exact second.
Throw
Wall slam - From a grab or behind cover
Throwing guard at another
Delayed punches
Rocket Arm
Grenade launchers - FAKEL, DGL103, ZORN-KP
Magazine to face - Only possible in reflex mode
S1000 AIR-S shotgun
Stun arm
Decoy activation
Stun decoy
Bionic arm
Stun grenade
Supply drop
Riot SMG
UN-ARC-NL Assault rifle
URAGAN-5 AIR-S revolver
RASP TB-SG AIR-S shotgun
D-Dog stun suit
Choke
Kick
3-5 Punch combo - 3 from the back or 5 from the front
Stay Tuned This Guide will soon be updated with new weapons and its durations