Ever thought the current Battle Rifle's barrel was a bit short? 
A bit late to the party, about 8 months too late, but I finally found a way to fix the muzzle flash.

This mod extends the barrel and muzzle to match its IRL counterpart's length, I used the FAL from Max Payne 3 as reference.
However the Muzzle Flash is misaligned as a result. I tried moving the Gun_Muzzle bone forward to match it but it doesn't seem to be working. Tried ticking the limit and unticking X Y Z and still no dice.
For now the only fix i managed to do was manually fixing the offset in the .meta file.
If you modified it yourself, just search for MuzzleOverrideOffset and change x=650.

Highly recommended to be used alongside  HeySlickThatsMe's Magazines: 
https://www.gta5-mods.com/weapons/vom-feuer-battle-rifle-improvements-replace
(All the preview images were taken with them)

I also fixed the HUD icon to match Slick's magazines and removes the weird line that got added with the Bottom Dollar Bounties update.

Default replace installation:
Weapon: 	\update\x64\dlcpacks\mp2023_02\dlc.rpf\x64\models\cdimages\weapons.rpf\
Meta: 		\update\x64\dlcpacks\mp2023_02\dlc.rpf\common\data\ai\
Hud: 		\update\update.rpf\x64\data\cdimages\scaleform_generic.rpf\hud.ytd
find and replace weapons_dlc_bd

Recommended installation:
If you still want to keep the original files and don't want to copy the entire dlc.rpf to the mods folder, I highly recommend using Groan's Patch: https://www.gta5-mods.com/misc/convenient-dlcpack-for-cosmetics-replacers
and dragging the models into the weapons.rpf
Alongside that, you should put weapon_battlerifle.meta into the update.rpf archive, the location should be:
\mods\update\update.rpf\dlc_patch\mp2023_02\common\data\ai (if no ai folder exists, you can create it)

update.rpf gets updated every time Rockstar decides to patch the game so keep that in mind.

Enjoy :)