"I want to become who/what I want to become" is strange in English. It's hard to say exactly why because I think I know what you mean, it could be because it's tautological (meaning it's saying the same thing twice). Okay, so if "I want to become X" then X must = a state or an object. For instance: "I want to become happy" or "I want to become a sailor". However the state "who I want to become" is vague and only restates the first part of the sentence. If I were to reword your sentence how I interpreted it it would be: "I want to become the idealized form of myself that I now hold in my head". Yet this still sounds strange because there are simpler ways of expressing a similar idea, like "I want to improve" or "I want to be a better person". Finally, I should add that in a specific context your sentence would work, for instance: Mary: I want to become a politician John: but politicians are all liars! Why do you wanna become one? Mary: what can I say? I want to become what I want to become In this context it simply restates the argument, here Mary is saying something like "I already told you I want to become a politician, and that reason alone should suffice". Last thought, using "be" instead of become seems to slightly improve the sentence: "I want to become who I want to be", or even better "I want to become the person I want to be". These sentences are all grammatical but still sound unnatural and weird to me, I think because as I mentioned above the meaning is tautological.

Yeah I take that to mean it's on the outside of his throat, for if it was inside his throat it would say "down his throat". The sentence is a little confusing because its kind of odd to shove a gun butt in someone's throat, would make more sense if it was the gun's barrel, which is from where the bullet shoots. Also, when I think of a gun butt I think of the end of a rifle, and google images seems to share this view. As a Jericho is a pistol it would be more correct to say "pistol grip". Even for an English speaker this sentence is unclear and it appears to me to be the fault of the author (or editor).