I just want to know, is that a cheating way to unlock a gun?

Teaming up with friends to unlock weapons is no cheating in my opinon .. as far as I know this would be called "statspadding".

It is unfair and against the TOS! It can result in a FairFight ban!

Oh, thank you. Is there any expert who can share his experience now?

Just play the game like a normal functioning person.

If any expert sees me, please answer me. I am like a headless fly in BF 4. I don't know how to find enemies, so my KD is very low. I don't want to go back to BF3

The guy above, with the name in orange, that says administrator below the name.... He's the expert, he's the one who bans people and handles ban appeals.  He told you to play normally.  Just play the game and you will unlock weapons, just like thousands of people before you have done.  If you kill trade, you may be banned automatically by the bot, or have your stats reset by fairfight, which will lead to a permanent ban here.

Take the administrators advice, just play the game normally. He is the expert.

If you are trying to know how to get better at the game, it's a fairly old game with tons of tutorials online. Just find one of them.

Trading kills with your friends is not cheating. It is against EA's Terms of Services and can result in a FairFight ban if someone gets a tickle up their butt. We haven't seen it happen but it can.

If you are going to trade kills with your friends because you suck and can't bother getting good at a 6-7 year old game then I DO NOT GO for headshots. Again, let me repeat it DO. NOT. GO. FOR. HEADSHOTS that will trigger most anticheats such as AdKats and even our automated bot and you will be banned, you will need to appeal and waste our time in looking into your appeal.

So TL;DR: not cheating, don't go for headshots. GIT GUD.

OK

I think I may have to get closer to the Ludus