The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

I could grab my RIFLE, crack your skull,
leave you fucked...
Money Heist Season 3, Episode 5

Sheldon, you got him in your sights. Fire!
He's charging his plasma RIFLE.
The Big Bang Theory Season 1, Episode 7

the RIFLE of my father's friend went off.
Money Heist Season 1, Episode 6

and fired on me with
what I ascertained to be
an M16 assault RIFLE.
Breaking Bad Season 2, Episode 3

Either you tell me the fucking PIN
or I’ll blow you with my RIFLE butt.
Money Heist Season 1, Episode 1