It K Dot got small arms you got long ones cuz this shyt sounds like a reeeaaaaachIV is slang for gun suppressors, ie silencers you attach to the barrel. He's saying he has small arms (like a T-Rex) but the IV evens things out.
MC Eiht had a rhyme about IVs on Maad City too.

But the way you explain it does sound plausible

The wording is just all fukked up.
I'm a lyric/bars lover like you, AkaDemiK. Get out your feelings for a second.nikka shyt the fukk up...because a nikka ain't dumbing it down for us dumbass don't mean other nikkas don't appreciate it
I listen to rappers equally if not more lyrically complex than Kendrick, most of his shyt usually doesn't require dumbing down.