The SMG-Issimo is like having a miniature flamethrower. This SMG is one of the unique weapons you will find scattered across Yara. The game will tell you to search La Raja Bar but won’t give you any other directions to find it.
What makes this weapon great is that it comes equipped with a suppressor, incendiary rounds, and the Reload All mod that reloads all of your weapons whenever this weapon is reloaded. Amazingly, Far Cry 6 classifies this weapon as a Rank Two weapon when it should probably be considered a rank three at least.
Take a look at the image above for reference to reach La Raja Bar. It is located in the Lozania region of Yara by the Caverna River. You can easily fast travel near this location if you have Hideout Trova, the Colinas Plains Checkpoint, or the F.I. Escudo Steel Plant unlocked.
Once you arrive in the area, you should find a bar under a large cliff area next to a river. There may or may not be enemies in the area. If there are, it will only be a couple that can easily be taken out. The chest will be waiting for you straight ahead of the bridge that goes over the river on top of some pallets.