It does add a crafting workbench where you can actually craft all of these guns, but I never use it, because I don't feel like it's very lore-friendly or immersive. You still find vanilla guns throughout the game, but not any more or less than other guns. It has a reflex scope, fires 5.56mm with a 20-round magazine. The Ruger AC556F replaced it and was marketed for military and law enforcement use.

It also leaves in the vanilla guns, but makes them make more sense (gives them applicable names, I believe straight from the earlier Fallouts - like the 10mm pistol is now the Colt 6520 - and changes their calibers if necessary - like the battle rifle now shoots a rifle caliber instead of a. The Ruger AC556F, created in the 1970s by Ruger, is a development of the Ruger Mini-14, an old assault rifle originally used only by police forces. It adds all of these to the levelled list, so that you find them naturally in your travels - and it seems to do this seamlessly, so that you find comparable weapons to what you'd find in vanilla (pipe guns and mosins early on, some carbines and hunting rifles a bit later, full auto 5.56s and AKs much later). It adds a whole slew of guns - 1911s, Glocks, Mosin Nagants, M1 Garands, Ak-47s, M16s, etc - as well as suitable calibers for them (9mm, 10mm, 45 ACP. It's basically a mod that takes a bunch of other weapons mods and combines them into one (there's a list on the Nexus page)

Weaponsmith Extended is a fantastic mod that, IMO, fixes the goofy Bethesda guns perfectly.

Fallout 4 nexus assault carbine