Problem #1 is occurrence. If you play enough, you'll see a shotgun every single looting area.
Problem #2 is reload speed. You can kill someone with any shotgun, (not counting the mozambique, that is still a joke) while missing 2 shots against a player who has not the best tracking skills.
Problem #3 is movement speed in the game. You can jump on the enemy, covering 50-100 meters in seconds. Switching the engagement from mid range to close range in that time. Take these facts and the dps that any shotgun can do with a blue bolt, and there you have it.
Yes, you can melt a shotgun player with an r-99, but that requires at least 1 purple item,which is pretty specific, and spawns far less than a shotgun and a bolt. And then you still need above average tracking skills, plus purple armor at least. This is how you can defeat an average shotgun player. I think these requirements are not really in balance.
I get that running on the enemy's face and blasting with a shotgun is fun, I do it occasionally, but this is too much. Feels like the game is forcing shotguns on people. From a balance perspective this is not good.
Changing my playstyle when the final ring is around is not something that's doable...
Landing with another squad and getting literally any other weapon than a shotgun against a shotgun is also something that is hard to dodge. Yes, I know that luck has a role in this game, but placing that many shotguns somehow makes it unfair for people who don't like to use them.
So nerf idea is to remove bolts and reduce "stock" fire rate at least to half of the current ones. Make it require skill to be good with a shotgun.