Best Calibers for Dinosaurs

tyrannosaurus rex in forest

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.

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.

big bore break-action rifle

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.

rifle with scope

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.

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.

pterosaur flying above dinosaurs

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.

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

Hornady Rifle ammo and box


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.

man holding lever-action rifle hunting dinosaurs

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!

About the Author:

John Bibby

John Bibby is an American gun writer who had the misfortune of being born in the occupied territory of New Jersey. His parents moved to the much freer state of Florida when he was 3. This allowed his father start teaching him about shooting prior to age 6. By age 8, he was regularly shooting with his father and parents of his friends. At age 12, despite the strong suggestions that he shouldn’t, he shot a neighbor’s “elephant rifle."

The rifle was a .375 H&H Magnum and, as such, precautions were taken. He had to shoot from prone. The recoil-induced, grass-stained shirt was a badge of honor. Shooting has been a constant in his life, as has cooking.

He is an (early) retired Executive Chef. Food is his other great passion. Currently, he is a semi-frequent 3-Gun competitor, with a solid weak spot on shotgun stages. When his business and travel schedule allow, you will often find him, ringing steel out well past 600 yards. In order to be consistent while going long, reloading is fairly mandatory. The 3-Gun matches work his progressive presses with volume work. Precision loading for long-range shooting and whitetail hunting keeps the single-stage presses from getting dusty.
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (26)

  1. There is one gun that could shred any dinosaur and I mean literally shred them the M2″Maduce” it is chambered in 50 BMG and is fully automatic it could rip holes in a t-rex and punch holes through the Armour of an Ankylosaurus so that is what I would choose.

  2. First, I would send my friend out with the largest, best rifle…(who would probably be way too gung-ho anyway) If they don’t make it back, I would stay put & live with off of the supplies as long as possible, and hope for another time rift.

  3. Since the only way to hunt a Dino, whether it be a T-Rex or an triceratops, is to travel back in time, I’d say you should avail youself of military gear on your way to the time machine. I.E. the military would be in charge of securing the darn thing. With that in mind, I’d go with the GAU-8 Avenger out of an A10 Warthog. Although, the depleted U rounds MIGHT be a little overkill. 😉

  4. If I was forced to hunt one on foot I would probably use a belt fed m79 (40mm grenade launcher) . They had a really nice trench sweeper round that was steel bearings in the “00” buck size if I recall. If not on foot than a Cobra helicopter or I would go with the gentleman in the New Jersey.

  5. If you want to read a short Time Travel story about just this subject find a copy of “A Gun for Dinosaur by L. Sprague de Camp” online.

  6. First of all I wish writers would use correct terminology. Stop using caliber when you mean cartridge. The caliber is the bullet diameter. If you recommend the .458 caliber that’s cool but which cartridge? The .458 SOCOM, 45-70, 458 Win Mag, and 460 Weatherby are all the same caliber but very different cartridges and power factors. All seriousness aside though I’d go with the Anzio 20mm for the big dinos. I doubt any T-rex would survive an HEI round to the side of the head.

  7. .50 caliber machine gun with explosive rounds. I’d want it dead fast and with the .50’s firing rate, that would do the job.

  8. Love my .45 Cal., HOWEVER, I would defer to the .50 Cal in this case, belt fed, with extra barrels, and lots and lots of ammo, just in case!!!

  9. I think we can all agree that the police in old Hollywood movies, shooting at dinosaurs with their revolvers, were way off the mark.

  10. Being career Navy, I would decide on USS New Jersey’s 16″ gun mounts. Big bullet, good range and lots of armor plating for protection!

  11. My choice for taking down a T-Rex would be the M1 Garand U.S. Service Rifle with the 8-round enbloc clip. As to Ammo I would use the .30 Armor Piercing M2 “Black Tip”. I would aim at the knee joint where the Tibia, Femur and Patella intersect.
    It matters not how much muscle, bone or ligaments are there, the Black Tip will wreck the joint and Dino will go down. Just a classic “Break Down Shot. I would want to stay clear of its tail and other leg as it will likely be thrashing about and or spinning. With careful stand off distance, one could then dispatch the animal with brain or spine shots.

  12. I would take the M1A2 Abrams I rode through Fallujah in. Pintle mounted 50 BMG & 7.62 NATO, plus room for a variety of personal weapons if warranted. Not to mention 2′ of armored plating and the 120mm if things go pear shaped

  13. The classic science fiction shot story from 1956 by L. Sprauge De Camp is “A Gun For Dinosaur”. Available on web as a free PDF.

  14. Personally, I’d select a 105mm sabot round from a safe standoff distance to ensure proper penetration.

  15. I don’t know that the caliber matters. But, hear me out…
    I do know for a fact that you must stay on the Path as directed to take your dinosaur (Do NOT leave the Path) because the butterfly effect is a real B!+©#… Don’t believe me? Just ask Mr. Eckels. No one wants to hear that SOUND OF THUNDER!!!

  16. If you were going with the bone crushing rifle method v/s the well-placed shot/small caliber method——just use an army tank?

  17. I think a .223 or 22-250 target rifle, combined with great knowledge of the anatomy & structure of each species of dinosaur would be more feasible than trying to kill them with a powerful, bone-crushing caliber.

  18. At first glance of the article title, I thought the writer was referring to old dog greybears who grew up with shooting and refusing to shoot anything less that .45 caliber pistols and haven’t changed their mind to this day because they were stubborn ol’ dogs they were.

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