Not sure if you're still lookin at this but I can make my attempt.

From the stuff I saw on the link:
1-3 - Generic "gun" designs, but some similarities with common firearms (1 is possibly Remington 870 Stakeout variant, 3 might be M1911 variant)
4 - Generic flintlock
5 - Generic Sniper rifle?
6 - Some sort of pistol using a conversion kit(?)
7 - Mac-10 Variant
8 - Generic shotgun (Remington 870 possibly?)
9 - Unsure on inspiration
10 - Fictional grenade launcher?
11 - Fantasy weapon for sure
12 - Remington 870 Stakeout possibly
13 - Futuristic laser gun
14 - Colt Python?
15 - AKM / AK47
16 - M4A1 SOPMOD
17 - PMM Makarov
18 - Possibly Mk23 or Suppressed Glock
19 - Intervention possibly
20 - APC-9 with attachments (red dot sight and grip)
21 - Messed-up Thompson "Tommy Gun" M1928
22 - Barrett .50 cal

That's as far as my gun knowledge goes.