Is there such a cheat?

Hey, I come here today to ask anyone with a fair bit of cheating experience in SAMP a couple of questions.

A friend of mine was banned today for using "damage mods", he says he doesn't and doesn't know what they are. Personally I've not heard of them either, but I've been away from the SAMP scene for a couple of years.

He was told he wasn't taking damage from certain weapons, e.g he would lose health to a chainsaw and a deagle, but not a sawn off. There was also the accusation that he doesn't take as much damage from certain weapons, I assume this means a deagle shot doing half the damage it should.

My question is this: Is there such a cheat? Is it possible to make you not take damage from certain weapons, but you will from others? Is it possible that you take less damage per shot from certain weapons? If so, is this cheat available to the public, and would we be able to prove it wasn't used via screenshots of his game?

Please note this happened when all targets were moving, all with around 200+ ping and fpslimit on 20.

Thanks for any help you can provide.

edit: for some reason there is a huge white gap below my post, I have no idea how to remove it.