UAC rifles: it seems to me rather large, cumbersome: perhaps it could be reduced in order to make it more compact and more "squared", like the current one which has a rather angular but original design
I actually DESPISE the bullpup carbine's look, so much that I sell them off and never use them. I just haven't bothered to remake it like some chinese rifle. RCF stuff is pretty useless except the scoped carbine, which is good for training weak pirates (and EP rounds are better in high accuracy weapons). But really the Compact Carbine and Zeerust Rifle are where its at when you get them, and for EP you might as well just use Shiny Niner and Ol' Carbine (80 or 64 damage)
The real reason I imagine for the UAC Rifle looking as it does - because of the design of the rifle carried by zombie trooper sprites in the original doom games. Which is, in a bizarre way hard to actually draw since its low resolution and drawn at an angle.
But It Looks Really Cool.It was supposed to be an m-16 I think but it wasn't modelled that way, heck you could even interpret it as a bullpup of some kind similar to the vhs2/hellion. And in original game the pistol was supposed to be a rifle, which is why the Chaingun uses the same ammo as the pistol and leads to interesting discussions. The answer to those discussions could be found in n64 doom by having the pistol be a desert eagle with a 10 shot magazine (the .44mag desert eagle model technically does have a rare 10 shot extended magazine, but its about as rare as the 12 shot Barrett M82 .50 cal magazine). A heavy goofy submachinegun firing .44 magnum actually sounds feasible at short to medium range, it hits like an AK. And soviet style bullet-pulling mechanisms and gas-operated (but heavily governed) action systems is how you would make a multibarrel machinegun work with any semblance of reliability (soviet gatlings and miniguns dont use electric motors).
But anyway I think the reason X-Piratez' rifle shoots 3 pellets is also a throwback to the original game where the Sergeants firing a Shotgun would emit 3 pellets in the same very wide firing arc every other zombie shoots in (which was a massive 22.5 degree spread I believe). Basically take 3 shots all at once, and that is the same codepointer action that the chaingunner and 20 health zombie trooper uses too. Was kinda-sorta meant to suggest doomguy's always -worn body armor layer soaks shotgun pellets so you only take moderate or chip damage from the blunt force (at most 45 points at point blank range, and thats if each of the damage dice roll "5", average would be 24-30). Poor way to emulate that, just like the super shotgun too, but it was hard to see those mechanics and they had to keep CPU usage to a minimum. Until you played deathmatch and the shotgun turns into a DMR pretty much.
To finish this boomer autistic rant, the original UAC Rifle pretty much looks like that except this one is even better and I think whoever made the current version nailed it. But it should basically be shooting Commando Pistol clips and that just doesn't make much sense. Keep in mind the original Chaingun also used pistol clips like the rifle and each ammo box came with 5 of them, so you could imagine 5 magazines jammed into the bottom of the chaingun and it just somehow auto-switches between each one until they're all done, then like a typewriter kicks them all out of the bottom to make more room. Ahh its like Action Movies from the 80s or that painful Wolfenstein 3d cover image where B.J. has an M-16 with multiple barrels firing at the ceiling.
edit -
The UAC Rifle is a rather powerful and destructive weapon which is 3 times as powerful as a standard assault rifle. So its size and chunkiness are justified.
The suggestion does give me inspiration to make a greenish Bullpup Carbine replacement built out of uac rifle parts though.