I have often heard talk across the Internet that at some point, the Assault Rifle found in Fallout 4 was to be known as a machine gun. Looking through the GECK, I have not noticed any evidence (chalk it up to me still being new to this whole modding thing), but the Art of Fallout 4 states that the Machine Gun became the Assault Rifle, and the gun we have in the final game is so bulky that I feel it needs to be mounted on an APC, not held in two hands (barring Power Armor of course).

This mod does two things:

A. The Assault Rifle is now named 'Machine Gun'.

B. References to Assault Rifles in the loading screens now refer to Machine Guns (granted, you could very well be using mods that add in Assault Rifles, but I'm making this mod assuming you haven't installed something along those lines just in case).

Have fun with the rename.