The M4A1 is by cocknose, awesome name btw, and you can find it here: https://www.nexusmods.com/fallout3/mods/5141

The AK47 is also by cocknose, you can find it here:
https://www.nexusmods.com/fallout3/mods/5258

The Spas12 is by Clint1337wood, you can find it here:
https://www.nexusmods.com/fallout3/mods/5258

The XM-586 is a Mothership Zeta Crew weapon, originally created by nylonathathep, found here:
https://www.nexusmods.com/fallout3/mods/8747

- (In regards to the XM-586) I created an optional file that includes a new version of the rifle for people, like me, who do NOT use the Mothership Zeta Crew mod. I took away everything from the Zeta Crew mod and placed the weapon into Chief Gustavo's inventory. This is a standalone version and does not require you to download the original.

I'm open to requests if there's a weapon mod on Fallout 3 Nexus that you want iron sight compatible. Just be sure to leave a comment! I'll do my best but not all weapons can be fixed.

All of these weapons are built around my animation mod found here:
https://www.nexusmods.com/fallout3/mods/25102