As a child of the 90's, I freaking LOVE what I always used to call "shoot'em up" movies. Here are I guess 5 of my favorite I can think of.
Anyone who knocks on some of these because they're dated can kiss my rear. FYI, this is not a list of the realest or best made. Just movies I like where they shoot alot.

1. John Wick (the first one but I really enjoyed 2 and looking forward to 3)
2. The Rock - an action movie classic
3. Face Off
4. Shooter
5. Desperado, Selma Hayeck fine now she was crazy fine in that one

What's in everyone else's top 5(ish)?

Not in my top 5 but Smokin Aces has some good stuff, particularly the 50 cal

Shoot 'Em Up with Clive Owen is a guilty pleasure.

Heat, of course. Really good shootout scenes.

Die Hard

Rambo movies

original Predator

Guigly Down Under and Enemy at the Gates

Oh, there's some good one's out there.

American Sniper
Shooter
Enemy at the Gates
Sniper (Tom Beringer classic, it's so bad but so good, and we laugh when watching)
Open Range
Unforgiven
Lethal Weapon

Dang it, i forgot that one. Nice once.
Ole Vasily Zaitsev is one bad mother...ohhh shut your mouf! And that German major by Ed Harris we too cool. They even used the period correct rifles and reticles (at least I remember the classic German reticle).

Edit:
American Sniper, it annoyed me that a-holes (and I'll go ahead and say that the vast majority were liberal ones in hollywood and media) kept harping on that stupid scene with the fake baby. To somewhat a small source of shame/regret, I've never been in the military. But what did seem real to even an outsider like me is the portrayal of a man (in the most basic sense of the word) who struggles with internal morality of taking a life whether justified of not in a legal sense and the very real struggle that men of these type have in their personal lives to which their families often pay the price.
But no, a stupid fake baby (the most trivial thing about even that scene) was the thing you heard the most.

Winchester 73.

Mine would probably all be westerns.

Tombstone
Good, Bad and the Ugly
Sicario

The Wild Bunch - #1 shoot em up movie ever made
Go Tell The Spartans
Saving Private Ryan

Still thinking about last two

More than 5 and not in any order.

Snatch
Win73
American Sniper
Enemy at the Gate
Shooter
Sniper-Guilty Pleasure
Dirty Harry
Lethal Weapons

Rough Riders - They had the discussion about new tactics since the regiment would be equipped with the first modern smokeless cartridges in their 30-40 Krag rifles. Previously most engagements were fought from behind a "smoke screen" because of all the smoke from the black powder cartridges. Also had a mix of period correct handguns. And to top it off, they actually found a couple of real Colt Potato Digger machine guns. And towards the end, the Rough Riders got their hands on some German Mauser's and were commenting on how great those rifles were.

I need to watch that one....

Open range
Wild bunch
Monte Walsh—not many shows have 86 and 87 winchesters
Saving Private Ryan
Sicario

I’m sure I’ll think of a lot more since it’s on my mind now.

Outlaw Josey Wales

Young Guns I
Young Guns II
Enemy at the Gates
Tombstone
Where Eagles Dare because I’m a huge fan of the MP40.

We watched Saving Private Ryan the other night, forgot how bloody and realistic it was. Great show!!

Quigly Down Under
Tombstone
Pale Rider
Outlaw Josey Wales
Death Wish

Most of mine have already been listed, I will second the Wild Bunch, Magnificent Seven would be on the list and this one.

https://www.amazon.com/Cross-Iron-James-Coburn/dp/B071X5BVHS

The Way if The Gun

I never think of Saving Private Ryan as a gun porn but I accept it now that everyone has brought it up.
It falls along the same path as Die Hard being a Christmas movie...technically correct is the best kind of correct.

I can't believe no one has said The Matrix yet. It had one of the most badazz gun scenes ever.

Black Hawk Down

Dirty Harry

the town
shooter
lone survivor
mr. and mrs. smith
deadpool

Quick and the Dead !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sharon Stone, Gene Hackman and a young DiCaprio

Awesome gunfights, Check out Stones "smoke wagon" She can work it !! DiCaprio has a pair of Nickle plated peacemakers and can spin em.

Young Costner in Silverado, twin nickle peacemakers. He trained with Thell Reed. famous fast draw champion for you younguns.

THE RIFLEMAN starring Chuck Conner.