If you are level 35 and under, then I may have some advice.
If you are a...
A) Person that recklessly runs out and starts putting lead into people, then I recommend using Akimbo P90's with rapidfire. Bullets fly EVERYWHERE! Just try not to die, because that is a dangerous weapon! Also have your secondary as Akimbo PP2000 with Extend Mags. Also have Sleight of hand perk on! And you HAVE to equip the Bling Pro perk!
B) A person that uses their brain rather than stomping out into the middle of battle with an AA12, then A SCAR-H Undermount-Shotgun with ACOG scope is right for you! Take your time to hide behind a crate for a bit. Remember, you need to have the Bling perk attached.
C) A Sniper, Then Use the Barrette 50.cal with Thermal attached. USE THE COLD-BLOODED PERK SO PAVE LOWS AND SUCH DO NOT PUT A GIANT HOLE IN YOU! Get in a shady place with some cover, get prone so you have better accuracy. For your own safety, do not use a sniper while playing on Rust, you WILL get torn to shreds...
I hope this helped a little bit at least....
Some low class weapons have great value for low level character.
I am actually refer to M4 here, it has a better range and decent accuracy, so in some cases it can outmatch Tar 21 or Famas, the fire rate is more of a make up for the low damage. I found it comes handy when playing before lv 48, when I unlocked the ACR.
I think most of the time for people who rush to the high traffic area, the weapon stats sometimes mean alot less (except MGs & shotguns). A smart way for some map is to avoid group rush or sitting duck with some teammates only trying to get ride of a sniper, in case u haven't notice, a predator missile might be aiming at u.
Also, for people with a play-to-win attitude, I think it is important to pay some attention to the sky. Yes shooting down a harrier does not earn u any kills but I think prevent kill-streaks can be equally important as it denies enemies' tactical advantage.