Bought a Desert Eagle in 50AE and have plans to use it for deer hunting on occasion. Pistol has a built in picatinny rail on top. Currently own a couple of Burris Fastfire III’s and they are OK but it’s a good time to try something new.
Looking for small, maybe 4-6 MOA dot. Range will be 25-50 yards

I just bought my first reflex red dot for a handgun. I haven't even tried it out. It's a cheap one. If I like it, I am going to buy a really nice one. I like Trijicon, but they can be a bit pricey. Are you thinking reflex or the more traditional style red dot?

At that range any of them will work fine...

Do you have a preference?

Look for one that’s rated to withstand the recoil of your little cannon, and also the whack of the slide returning to battery. Not all will, for long anyway. Durable usually means expensive, sad to say, as in Aimpoint.

My RWS Air King finally made the Sparc 2 it wore lose zero after a pretty good run. Don’t know yet it it’s broke or just jumped the tracks. A mere .357 killed another after about 10 rounds, as in tore the LED inside loose. They replaced it with another, of course, but those are alleged to be one of the tougher ones, on YouTube anyway. A first-gen FF rode another .357 for a good while with no trouble, so maybe you should try one of the ones you have.

Aimpoint. No question.

Your only serious options are the Trijicon and Aimpoint. Buy it now or buy it after something else breaks.

That’s the dumbest thing posted in 2021.

Read some favorable comments about the Vortex Venom from guys using them on hard recoiling revolvers. Think I will try one,

Aimpoint, Trijicon or Leupold DPP-- every other brand that I've tried has gone down on me, especially on semi-autos.

For the level of recoil and slide velocity generated by a Desert Eagle you will need a very sturdy red dot. I would agree that Aimpoint and Trijicon are probably the best bets.

What other brands have you tried and how did the manufacture handle the issue?

The scope rail is part of the barrel not the slide correct?
So it shouldn’t get too beat up. I have two Trijicon RMR’s and both have withstood a lot of pounding so far on a 9mm M&P and a 10mm Ruger 1911.
The RM-06 was also on two Smiths a 629 and a 657.

I have a Holosun on a pistol. It's held up great. I have a venom on a 3½" magnum shotgun it's held up fine. I prefer the Holosun on the pistol as I can change reticles by pushing buttons. I believe Holosun is the largest manufacturer of red dots in world. If you are looking at the reflex sights from a purely ruggedness perspective the the Trijicon RMR wins

I would agree with this; but, I would add the Shield to that list.