Time it takes to kill a Tank on Expert difficulty. (From my own solo testing)
[ SIDEARMS ]
Dual Pistols ~54 Seconds
Magnum ~1 Minute 6 Seconds
Pistol ~1 Minute 22 Seconds

[ MELEES ] - Melee damage is calculated as: Max Tank health times 0.05
3,000 (Easy) - 150
4,000 (Normal) - 200
6,000 (Versus) - 300
8,000 (Advanced/Expert) - 400

Chainsaw ~8 Seconds
Police Baton ~12 Seconds
Machete ~13 Seconds
Riot Shield ~14 Seconds
Golf Club ~15 Seconds
Katana ~15 Seconds
Knife ~15 Seconds
Baseball Bat ~16 Seconds
Cricket Bat ~16 Seconds
Pitchfork ~16 Seconds
Frying Pan ~17 Seconds
Fire Axe ~18 Seconds
Crowbar ~18 Seconds
Guitar ~18 Seconds
Shovel ~19 Seconds

[ TIER 1 ]
Silenced SMG ~33 Seconds
MP5 ~43 Seconds
SMG ~45 Seconds
Pump Shotgun (Shove tech) ~46 Seconds
Chrome Shotgun (Shove tech) ~47 Seconds
Pump Shotgun (Full reload then shoot) ~48 Seconds
Chrome Shotgun (Full reload then shoot) ~49 Seconds
Chrome Shotgun (Reload once then shoot) ~51 Seconds
Pump Shotgun (Reload once then shoot) ~53 Seconds

[ TIER 2 ]
AK47 ~26 Seconds
Spas Shotgun (Full reload then shoot) ~28 Seconds
Auto Shotgun (Full reload then shoot) ~30 Seconds
M16 ~31 Seconds
SCAR ~32 Seconds
Military Rifle ~33 Seconds
Spas Shotgun (Reload once then shoot) ~34 Seconds
Auto Shotgun (Reload once then shoot) ~37 Seconds
SG552 ~35 Seconds
Hunting Rifle ~44 Seconds
AWP (Shove tech) ~1 Minute 13 Seconds
Scout (Shove tech) ~1 Minute 21 Seconds
AWP ~1 Minute 28 Seconds
Scout ~1 Minute 30 Seconds

[ SPECIAL ]
Grenade Launcher ~30 Seconds
2 M60's ~19 Seconds

[ REBALANCED ]
M60 ~14 Seconds
SCAR ~28 Seconds
SG552 ~32 Seconds
AWP (Shove tech) ~41 Seconds
Scout (Shove tech) ~46 Seconds
AWP ~47 Seconds
Scout ~52 Seconds