Jericho 941 is a mod that adds a Jericho 941 into Fallout 4. It will spawn on any boss, including the Gunners boss, and KL-E-0 will sell it. It has been added to the leveled lists.
As soon as your character reaches level 10, it will begin to spawn.

The weapons in this mod are the following:

Barrels

Standard Barrel / .38 Caliber

10mm Caliber Conversion Barrel

.45 Caliber Conversion Barrel

Sights

Standard Sights

Glow Sights

Magazines

Standard Magazine

Quick Eject Mag

Medium Magazine

Medium Quick Magazine

Large Magazine

Large Quick Magazine

Receivers

Standard Receiver

Hair Trigger Receiver

Heavy Frame Receiver

Light Frame Receiver

Hardened Receiver

Powerful Receiver

Calibrated Powerful Receiver

Advanced Receiver

Cheat Receiver

Grips

Standard Grip

Wood Grip

Samurai Grip - Black

Samurai Grip - Brown

Samurai Grip - Blue

Samurai Grip - Red

Samurai Grip - White

Sharpshooter's Grip

VATS Enhanced Grip

Mount

Flash Light

Katana Bayonet

Color

Black

Silver

Silver Slide

Silver Frame

Muzzle Mods

Compensator

Compensator Type - DE

Suppressor