From a design standpoint, I don't like how bulky and oversized the weapons in Fallout look, especially launchers and heavy weapons. To remedy this, I decided to try my hand at redesigning some of the more egregious examples, and these are the results. The meshes included in this mod replace the corresponding base-game weapons with my less-bulky “slimline” versions.
Unfortunately, a plugin is required to make sure the first-person textures are applied correctly. At the moment, there isn't enough information available to determine why the 3D index gets changed when editing a mesh, making a true ESP-less drop-in solution impossible for the time being. If needed, the modified records in the plugin can always be merged into another plugin to free up space in your load order.
I started with the base game 10mm Pistol mesh and removed the widget under the barrel, as well as reducing the size of the block it was attached to. I left a little bit of it because I liked the way it looked, and it arguably now functions as a barrel weight to reduce muzzle flip. Next, I shortened the barrel and lowered the sights so that the height-over-bore distance wasn't quite so egregious. I also slimmed down the profile, and if you look at it from the front, it's a good half inch slimmer than the base game model.
I started with the base game 12.7mm Submachine Gun mesh and removed the forward knuckle guard, then lengthened the pistol grip to prevent it from clipping through the player's hand. I then thinned down the width of the receiver and magazine, and modified the front end to create a blunt-nosed vented shroud look. I added the trigger from the Recharger Pistol, the charging handle from the Lonesome Road DLC's Red Glare, the charging handle slot from the Silenced .22 SMG, and the sight rail from the Laser RCW. The stock was made using the carry handle from the Missile Launcher and a retextured pump handle from Red Glare.
Meshes are included for both the base game and Gun Runners' Arsenal versions.
I started with the base game Incinerator mesh and removed everything except the barrel. I then added the front handle and trigger from the Fat Man, and the gas tank from the legacy-content welding Gun from Fallout 3's The Pitt DLC. I wanted the overall shape to look more like real-world WWII-era flamethrowers such as the M2.
I started with the base game Minigun mesh and shrunk it down by 15% to make it a more realistic size for being a man-portable weapon. I then rearranged some pieces to make it even more compact, before shortening the barrel. I then replaced the pistol grip and forward grip with the ones from the Plasma Caster. I didn't include a mesh for the unique minigun since canonically, it's a different make and model (A CZ57 as opposed to the generic CZ53).
I started with the base game Missile Launcher mesh and removed the control box, along with all the switches, dials, etc. I then mated the two separated halves together, and added the shoulder pad and trigger grip assembly from the Lonesome Road DLC's Shoulder Mounted Machine Gun. The modded version with the guidance system uses pieces from the Tri-Beam Laser Rifle. In my headcanon, this works like the RPG in the Half-Life videogame franchise, where the missile is guided to its target by an infrared laser.