Aaaah the Beowulf, the weapon that contributed to ruining my experience further. Not surprised to see it is the most used. The amount of ways in which that weapon was more convenient than anything else is ridiculous.
In semi-auto it hits almost as hard as anything else you can find, but you find it significantly earlier than most powerful things, and it shoots decently fast. It is very common loot so there is a big chance that you will come across one that is souped up, so you won't even have to modify it. It is flexible enough that it works at most distances. But...

But, but, but, there is something much much more important than any one of those things that makes it so that it is not worth bothering putting any effort into developing your arsenal beyond this weapon.
Do you know what is the most common loot from pickpocketing the extremely abundant security guards in the world? A loot considered so insignificant that you get a very high chance of stealing it even with relatively mid stealth and pickpocketing skills?
A bunch of 7.77 ammo.
Do you know what is is one the most common types of loot from the random bandits and pirates that you randomly kill by the bushload?
A bunch of 7.77 ammo.
Do you know what the Beowulf uses?
Exactly.

The game considers 7.77 ammon trash loot even though the Beowulf is a very decent performer. I had 1600 rounds when I came across the first decently souped up Beowulf. Why would I put any effort into using anything else? I ended up using that weapon for 75% of the game! What the fuck.