Best Calibers for Dinosaurs

Video gun rated to kill t rex

As most of you are aware, this is a question often brought up in gun circles. Admittedly, it is mostly as a joke.

The questioner is often talking about something BIG like a T-Rex, Anklyosaurus or a Triceratops.

The fact of the matter is, there were dinosaurs from the size of field mice up to Dreadnaughtus at 65 tons. Some of them were vicious, fast killers.

Others were slow and docile. Yet others were armored or could fly. Just like with modern game, each calls for a different thing.

Large and Dangerous Dinosaurs

Let’s start with the big and dangerous game options.

The minimum caliber for a Cape Buffalo (one-ton bull) is considered to be .375 H&H (300-grain Swift A Frame ¾ 2,560 fps/4,360 ft/lbs).

This is usually only when using a double rifle that allows a quick follow-up shot.

Most people chose something with a bit more hitting power, something in the .416 Rigby range (400-grain Swift A Frame ¾ 2,350 fps/4,988 ft/lbs) or greater.

The T-Rex was up to six times bigger than a Cape Buffalo, at six to eight tons and by all accounts should have been at least as ornery.

The people who invented the .577 T-Rex (750-grain Monolithic solid 2,480 fps/10,880 ft/lbs) may have been on the right path.

Many of you are going to suggest .50 BMG. That certainly is not a poor choice, but bullet construction comes into play here.

The 750-grain Hornady (2,820 fps/13,240 ft/lbs) is pretty potent. The problem is with the pointy FMJ projectile.

This can lead to bullet deflection and thin tunneling, as opposed to a wide wound cavity.

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The thing to look for in stopping massive creatures is a blunt-nosed bullet that crushes its way through bone and soft tissue.

Retention of bullet weight, moderate deformation and a slow, deep tumble are very helpful.

Don’t get me wrong, if I had to choose between a .375 H&H or a .50 BMG, I am going .50 BMG every time and on armored game, it might have advantages.

If I was planning a large and dangerous dinosaur hunt, I might also consider the distance and hitting-power options of an Anzio Ironworks 20mm Bolt gun.

There is something to be said for the thrill of up-close hunting, but there is also something to be said for the safety of sending a 1,500-grain (3,400fps/39,500 ft/lbs) projectile from 500 to 1,500 yards away.

Those numbers are before we discuss armor-piercing or high-explosive projectile options.

As aggressive as the T-Rex was assumed to be, the Anklyosaurus was an armored five-ton beast who may not have noticed being hit by a .375 H&H.

It may have been like attempting to put down a charging feral hog with .22 LR. A mature Triceratops probably weighed as much as 25 to 30 tons.

In comparison, the African bush elephant bulls top out at about 6.5 tons.

Again, I would assume the .375 H&H would not be a decisive choice even if you managed to avoid the armor.

Flying Dinosaurs

Of the flying dinosaurs, the Pterosaurs are the most well known. Most of these range in wingspan from 18 inches to about five feet.

There was a giant species known as the Quetzalcoatlus, which had a wingspan of over 33 feet.

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Despite its large size, the adults of the species only weighed about 250 pounds.

For the smaller versions, a shotgun with flight-control wads would work quite well.

Hunting them would not be much different than hunting oversized pheasant, although I would likely choose a turkey load as opposed to #7.5 birdshot.

Even the largest species would likely have succumbed to 00 buck. All flying creatures are less robustly built than similar-sized land animals.

I imagine the trick would be much like trying to hunt an eagle or a condor today (super illegal by the way), getting close enough.

If you were choosing to hunt them not in flight, almost any centerfire cartridge would work for the smaller Pterosoaurs.

The larger ones would probably benefit from something in the .243 Winchester class or better.

But even here, I would think there would be a lot of meat and trophy damage on all but the largest species.

Smaller Dinosaurs

The other large group of hunting options would be the dinosaurs ranging in size from Border Collie to Gemsbok.

For these “big game” species, the bigger issue would be how dangerous they are and if their social method is solo or pack oriented.


For the herbivores up in the CPX2 range, anything from .243 Win (2,900 fps/2,100 ft/lbs) up to .300 PRC 230-grain (2,900 fps/4,300 ft/lbs) would work.

The choice would depend more on how close you want to be as opposed to stopping power.

For larger herbivores in the CPX3/4 range, .308 Win up to the medium African big game cartridges might be appropriate.

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.416 Rigby does a great job with Eland, it would likely do just as well on an 1800-pound reptile herbivore.


For the carnivorous creatures of CPX3 or larger, I would want a bit more insurance, either in a bigger round or a couple of friends who also have a double rifle of appropriate caliber.

Both would probably be the better choice.

If .577 T-Rex (750-grain Monolithic solid ¾ 2,480 fps/10,880 ft/lbs), .600 Nitro Express (900-grain 2,050 fps/8,400 ft/lbs) or .500 Jeffrey (600-grain 2,460 fps/8,120 ft/lbs) were available choices, one of them would get the nod.

Stopping an angry lioness or wolf is no sure thing. Adding 800 to 1,500 pounds of reptilian anger would be even trickier to stop.

Not to mention their brains were proportionally smaller and their central nervous systems were more heavily protected.

Conclusion: Best Calibers for Dinosaurs

We can’t test out the theories as we lack dinosaurs to hunt, but I can tell you I would not be like the guy in Jurassic Park using a .45-70 lever gun.

Even the Ruger (strong) loads with a 300-grain projectile (2,275 fps 3440 ft/lbs) are not that great and the standard load is 600 ft/lbs lower.

The trapdoor load is anemic at just over 1,750 ft/lbs.

What would you bring for your dinosaur safari? Let us know in the comments below!

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Ethan Smith is a seasoned marine veteran, professional blogger, witty and edgy writer, and an avid hunter. He spent a great deal of his childhood years around the Apache-Sitgreaves National Forest in Arizona. Watching active hunters practise their craft initiated him into the world of hunting and rubrics of outdoor life. He also honed his writing skills by sharing his outdoor experiences with fellow schoolmates through their high school’s magazine. Further along the way, the US Marine Corps got wind of his excellent combination of skills and sought to put them into good use by employing him as a combat correspondent. He now shares his income from this prestigious job with his wife and one kid. Read more >>