The badass line to end all badass lines from the first film:
I know what you're thinking, punk. 'Did he fire six shots or only five?' Well, to tell you the truth, I've forgotten myself in all this excitement. But being as this is a .44 Magnum, the most powerful handgun in the world, and would blow your head clean off, you've got to ask yourself a question: Do I feel lucky? Well, do ya,'punk?'
Not to mention that when Harry starts to berate Scorpio he says "punk" with such force the actor's hair is blown back.
A somewhat convoluted, but surprisingly Chessmasterish moment from Magnum Force, Harry is in a shooting competition with a man he (correctly) suspects in a series of vigilante shootings; he (reasonably) asks to borrow the man's gun. The suspect, already in a Columbo-like situation, agrees. Harry proceeds to make a point to the suspect by shooting one of the "innocent" targets in the shoot/don't shoot target run. And then, that night, Harry returns to the shooting gallery, finds the innocent target he shot earlier, and uses the bullet he extracts from it to compare the ballistics on the vigilante shootings.
It should be noted that the "innocent" target was a cop.
Not that it changes much, but Harry shot the cop target with his own gun during the competition. It was after the competition was over when he shot a run with the other gun, and an intentional miss lodged the slug in a 2x4.
Also from Magnum Force, the very last use of "A man's got to know his limitations."
Yet another example from Magnum Force was when Harry sneaks up on a killer cop and fucking BEATS him to death.
And another for the film: the opening credits is a close up of a Magnum .44, near the end it is slowly cocked that right at the end Harry swivels it right at the viewer.
"This is a .44 Magnum. It's the most powerful handgun in the world. And it could blow your head clear owf. Do you feel lucky?" *BOOM!*
And Harry's Establishing Character Moment from this movie. He stumbles on an airplane hijacking, with the airport personnel waiting for another cop to infiltrate on the plane as the pilot, so he infiltrates on the plane unarmed and solves the situation, knocking down one of the hijackers and then using his gun to kill the other shooting through one of the plane's walls. Then, as he leaves, he meets the guy who got him on the stakeout squad and was the guy supposed to infiltrate the plane and takes the chance to mockingly ask what he's doing there.