that thing is seriously ancient, I can't believe it's still in use

"We live in an era of unmatched technological advancement in the field of small arms. I can't imagine what they'll be using a hundred years from now."
John Browning, struck with divine inspiration from the god of firearms: "I CAN"
- I'm sure he'd be rolling over in his grave if he knew they added a safety to it.
  
  Does the M2A1 have a safety? I thought they just gave it a quick swap barrel
- Colt 1911, accept no substitute.
  
  Two world wars and still has a valid NSN.
  
  Browning Hi-Power.

A gun so old they had to start callin it the Maw-Maw Deuce.
- And when you have 2 Maw-Maws under the same roof, hellfire upon those who dare not to have a second plate.
  
  Woe to the man who doesn't like sweet tea! Great shall be her anguish!
  
  I don't think two plates of anything are going to stop .50 BMG

I've had the pleasure of using one, and the reasons for its continued use are many, but I'll list a few:
Proven design that works well
Ease of maintenance (except from that one bit you absolutely have to remember to flip forward before inserting the bolt carrier, lest you have to drill in from the side to file it off to unjam the bolt carrier)
Objectively cool
Adds three inches to your penis size (men), a couple of letters to the cup size (women), or either/both for anyone else
NATO has literal tonns upon tones of ammo for it. Tha m82 shooter is sure as hell not removing the linked chains from all of it so he can carry it around himself.
- Trying to think of what bit you have to flip...
  Are you talking about the cocking lever? It needs to be pushed forward prior to pushing the bolt all the way forward into battery, because it catches in a notch at the top of the receiver in order to cock the firing pin (bolt goes back, lever flips forward, and vice versa). But if you put the bolt in with the cocking lever back, which people do a lot, the lever gets stuck on the timing arm attached to the receiver. Barely an inconvenience. But...
  Did somebody jam that sumbitch in there so good that you had to destroy the motherfucker? Because that is fucking insane. That's like breaking a steel framing hammer. Like, I get it, but... How!?
  
  It's been 20 years since I lasted opened an m2, so I don't remember exactly, but the part I'm talking about is a fairly nondescript metal piece sticking up from the bolt carrier. I may remember it incorrectly that it has to be back and not forward.
  Also, the drill + file is what I was told. I never saw it happen.
  
  Found it: https://pasteboard.co/oASJ7W28VB65.jpg

They're still using Maxim guns in Ukraine.
- Liquid cooled guns on a fixed position will shoot and shoot and shoot and shoot and shoot and shoot and shoot and shoot and shoot as long as they have ammo and some water in the sleeve. They are really good guns for ww1 style trench warfare.
  
  I'm reminded when a British battalion had to get rid of all their old Vickers ammo, and ran it through their old Vickers gun. I think they said they did like 2 million rounds and had 2 issues total.
- Really, the only thing "wrong" with them is that they're heavy as fuck. But if you're not moving, that's not a problem
  
  Or if ya mount them on the bed of a Toyota hilux.

https://en.wikipedia.org/wiki/M2_Browning
Apparently at one point -- I assume during the war -- Frigidaire, of all companies, was manufacturing M2 Brownings.
kagis
Apparently they made quite a few, actually:
https://usautoindustryworldwartwo.com/General%20Motors/frigidaire.htm
Frigidaire Division of GM World War Two Products: 363,000 .50 Caliber Browning M2 Aircraft Machine Guns, 1,000,000 spare .50 Caliber Machine Gun Barrels...Frigidaire engineers made over 500 design and manufacturing changes to reduce the cost of the machine gun to 25% of the original cost, using mass manufacturing techniques.
EDIT:
Apparently in 2015, some active-duty unit sent in M2 Browning Serial #324 for maintenance. This was the first time it had ever been sent in for maintenance.
https://www.army.mil/article/150794/Making_the_old_like_new
In more than 90 years of existence, the receiver with serial number 324 has never been overhauled.
"Looking at the receiver, for its age, it looks good as new and it gauges better than most of the other weapons," said John Clark, a small arms repair leader.

While there are many small bits of nuance from gun to gun, they mostly share a fairly straightforward design that doesn't have some groundbreaking design possibilities waiting in the wings. The Browning was built to be very reliable, has a lot of spare parts, and is maintained in an environment that stresses consistency. Yeah, they are going be to around for a very, very long time.
It is funny to find out that they were almost dropped by the military early on because they didn't live up to the niche they were originally designed for. As long as they are useful they will be around.

Well, as long as most of us are still squishy bags of mostly water, Ma Deuce will still be effective. Even if you’re wearing body armor a 50 cal is going to ruin your day. It’s old, but it still punches holes effectively.

Any piece of military hardware that can outlast the B-52 is probably doing something right.
- That race is still on though.
  
  True, but the B-52's got a successor coming in, and nothing's waiting in the wings for the M2.
- Whoa there we absolutely replaced the M2. We got the M2A1.
  
  Well, the receiver got an update, but if you're gonna count that as a replacement, the B-52 has had a lot of updates too.

Its one of those tools that just doesn't need to change, like a claw hammer or a monkey wrench.

Yep, definitely the cocking lever. Good job to the meathead who accomplished what nature could not!

too late and too early are flipped.

Forgotten Weapons talking about its history, including why it's still around:
https://www.youtube.com/watch?v=cmLnwiJRr78