The animations were originally from the Azure Sheep mod for Black Mesa, Shadow_RUN was kind enough to rig the animations with the HEV arms using an M4 model from tigg. I'm unfortunately not sure who made the reloading sounds, if anyone knows who made them please let me know so I can credit them.
For now this mod features new models, animations, and some new sounds (I personally really like the vanilla MP5 firing sounds so I kept those); this also uses the vanilla MP5 icon in the selection menu. Note that my game is heavily modded in the video; the muzzle flash, lighting effects, and headcrab are NOT part of this mod.
While this is in a usable state, I've put it under the WIP section for now, as this is an old mod that has been sitting on my PC for months now; Shadow_RUN has also told me this mod was rather sloppily put together. I'm also waiting for the Definitive Edition to get out of beta before I do any sort of official release. If anyone wants to make fixes you have my full permission, just please make sure to credit properly.
Unfortunately this mod exceed's GB's file limit by 8 kb, so it can be downloaded here