.577 Tyrannosaur: A Complete Review

As an Amazon Associate I earn from qualifying purchases.
Our Associate portal can be found here


The .577 Tyrannosaur, also known as the .577 T-Rex, refers to a large and extremely powerful cartridge. It measures 14.9×76 mm and was developed on request for professional hunting guides in Zimbabwe back in 1993 to be used in big game hunting. 

The basic idea was that the .577 Tyrannosaur was to be used as a stopping rifle to counter the charge of dangerous game. It boasts 14.9 mm diameter and a 750 grain Monolithic Solid Projectile, which fires at 2,460 ft. /s and produces 10,180 foot-pounds force of muzzle energy. The A-square’s production model is according to their Hannibal rifle. This bolt action rifle weighed 13 pounds and had three mercury recoil reducers.

Why is The 577 Tyrannosaur Popular?

It’s not wrong to say that the 577 Tyrannosaur wasn’t designed for the faint-hearted. As the name suggests, the maker of this round had the idea of producing a weapon that could exterminate a dinosaur with ease. 

Some rather shocking or fascinating videos making rounds online show unsuspecting shooters rocking and rolling with the 577 Tyrannosaur. It is incredibly powerful ammo, which produces excellent muzzle energy and recoil. It is a heavy-recoiling hunting rifle cartridge and works well for experienced shooters.

The rifle powerful enough to shoot this round usually weighs about 10 pounds or more. It is remarkably more robust than the .44 Magnum revolver round, which boasts 1533 foot-pounds of energy.

What Features Should You Expect with the .577 Tyrannosaur?

  • 10,180 foot-pounds of energy
  • 172 foot-pounds recoil
  • Shoots 750-grain Monolithic Solid bullets
  • Rimless bottle-neck case type
  • 14.9mm bullet diameter
  • 308mm rifling twist
  • Large rifle magnum- primer type
  • 75.9mm case length
  • 17.5mm rim diameter

How Powerful is The .577 Tyrannosaur Round?

This big game rifle cartridge has left many questions than answers regarding its power. Despite having enormous potential to crumble an elephant, many people fear using it. The combination of its ballistics proves where the insane recoil comes from.

With 13,800 J muzzle energy and a staggering 2,460 ft. /s velocity, this cartridge is no joke. All thanks to its 14.9 mm diameter and the 750-grain monolithic projectile. Some gun experts suggest that this ammo perhaps isn’t fit to be used or chambered in guns to be carried around. This suggests why this isn’t an ideal rifle cartridge for a tactic or shooting performance.

In comparison to the .308 cartridge, it’s proven that the .577 is four times stronger. One interesting thing is that it lacks enough speed to compete with most ammo used in tactical performances. Compared to the .308 ammo, it travels 200 ft. /s slower, but the energy delivered on the target is overwhelming.

However, we can’t conclusively say that the .577 is the champion in terms of productive energy. Compared to the .50 BMG, it is about 3,000-foot-pounds less. In recent years, its popularity has indeed been overtaken by the .50BMG among other recently-discovered range rifle cartridges. 

To counter the insane recoil, the developer of the .577 tyrannosaur Hannibal rifle had to increase the rifle’s weight. Amazingly, the recoil is still there despite the overweight design of the gun. But at least people can get a chuckle seeing some diehards shooting such a high recoil rifle.

What You Will Love about this Cartridge

  • Great knockdown power
  • Impressive velocity
  • Fun to shoot
  • Unique nostalgia
  • Competitive with modern ammo

The Not So Good

  • Insane recoil
  • Expensive
  • Complaints about inaccuracy

Which Gun is Compatible with the .577 Tyrannosaur Round?

A-SQUARE Hannibal Model Rifle

This was the original rifle custom made for the big game in Africa.  It is chambered in the .577 tyrannosaur cartridge, and the rifle weighed about 13.6 pounds. One shortcoming is that no effort was made to shoot in for group accuracy because the whole purpose of this rifle was to function as a last resort to stop charging animals. 

Most Popular Ammunition Accessories

[amalinkspro_table id=”2826″ aff-id=”” new-window=”on” nofollow=”on” addtocart=”off” /]

How Does the .577 Tyrannosaur Compare with Some Overpowered Hunting Cartridges?

The .700 Holland & Holland Versus. 577 Tyrannosaur

These two are among the hardest kicking rounds of all time. They are excellent rifle cartridges for big game hunting. The .700 Holland & Holland dates back in 1980 when Bill Feldstein ordered a .600 from the H&H but didn’t succeed. He opted for the .700 H&H, and the company agreed to his request. He then got his rifle after completing a development fee of $144,000 and $200,000 for the double itself. 

Considering the ballistics, the .577 Tyrannosaur beats this .700 H&H. The latter fires 1000-grain bullets at 2000 fps delivering muzzle energy of 8,900 foot-pounds. Also, these rifles are available in various models currently. The .700 H&H rifles typically weigh about 19 pounds. However, the recoil force is 160 pounds-force. The recoil is a bit lower than that of .577 Tyrannosaur, which is about 172 pounds-force. This recoil is, however, higher than that of .600 and .308 rounds.

577 Tyrannosaur versus .50 BMG

There are vivid differences and similarities between the performance and design of 577 tyrannosaur and .50 BMG cartridges. The maker of 577-Tyrannosaur had the intention of making ammo that could go through the standard bolt-action rifles, which was quite prominent in hunting during those eras. Hence, he made one the 577 Tyrannosaur with a case length limited to 2.99″. 

It features a case capacity of roughly 212 grains of water, while the .50 BMG offers about 289 grains of water. Looking at the capacity, the 577 tyrannosaur is similar to the .600 Nitro Express. The 577 tyrannosaur features 750 gr solid bullet rated at 2400 fps while the .50 BMG cartridge offers 720 gr. FMJ-BT bullet, which delivers 2810 fps muzzle velocity.

The 577 tyrannosaur cartridge offers 9590 fpe muzzle energy while its rival offers 12600 fpe muzzle energy. Therefore, you can agree with me that these two outstanding cartridges are ideal for hunting. They are in close competition in almost every aspect, despite the fact that the .50 BMG is slightly higher in terms of ballistics. 

The .50 BMG is quite competitive than the .577 Tyrannosaur in terms of long-range accuracy as well as follow-up firepower. But you shouldn’t underestimate the .577 cartridge in any way because it offers fantastic performance in terms of close-range and medium-range accuracy. It, however, produces high recoil, which many people can’t manage.  

.700 Nitro Express versus .577 Tyrannosaur Cartridges

If you would get into an argument whether the .577 caliber can stop a real T-Rex, I think it’s okay to consider its ballistics compared to .700 nitro express. The 10k ft. /lbs. the energy of .577 caliber is no joke, but still, .700 Nitro has something great to offer. In this case, it provides 9K ft. /lbs., which is slightly lower muzzle energy than that of .577.

Hence, these two are incredibly suited for dealing with big and dangerous games such as elephants. The .577 cartridge, however, features a lower bullet weight and a smaller diameter. This adds it to one more shortcoming compared to the .700 Nitro Express. In my view, the weight of the bullet is essential, in that it will ensure that it reaches the vital organs located deep inside the big game’s body. Professional hunting will appreciate rifle cartridges that deliver the instant humane kill.

The .475 A&M Magnum vs .577 Tyrannosaur

To appreciate the prowess of the .577 Tyrannosaur in the big game hunting, we’ve to compare it with the .475 A&M Magnum. The latter originates from the famous rifle-making firm of Atkinson & Marquart, an outstanding maker of high-grade rifles in Prescott, Ariz.

This round is necked from the .45 to .47, which made them compatible with 600-grain bullets. It fires them at an incredible velocity of 2,500 fps and 8,040 foot-pounds of energy. 

At this juncture, you can tell that this round is no match for the .577 Tyrannosaur. The recoil is 100-foot pounds, which is quite lower than the .577 T-Rex. However, they are very few since only a few of these rifles were made. You might be lucky to find this gun stocked by Griffin & Howe or other renowned gun stores.

The .600 Nitro Express compared to .577 Tyrannosaur.

There is no way you can embrace the toughness of the .577 Tyrannosaur without mentioning this great innovation by W. J. Jeffrey. It’s one of the oldest rifle cartridges which will be remembered for generations to come. It wasn’t used as a regular thing, and many hunters kept in camps to be used in direst of attacks.

The recoil was too high, and this round could only be chambered in rifles weighing 15 to 16 pounds to lessen the effects of recoil and make it shootable. It fires a 900-grain bullet at a monster velocity of 2050 fps, and muzzle energy is 8,400 foot-pounds. Therefore, the .577 Tyrannosaur also outshines this particular rifle cartridge. 

The recoil of the .600 Nitro Express is about 103 foot-pounds and is remarkable if you would compare it with .375 H&H, which offers 35 foot-pounds only. Hence, we can put the .600 Nitro Express and .577 Tyrannosaur in the same category without fear of contradiction.

Frequently Asked Questions

Is the 577 Tyrannosaur Legal in California

Since this hunting rifle offers profound hunting, many people want to know whether you can use it in California. Remember that this state is endowed with big games, and therefore hunting weapons need to be given some special attention. Well, most of the rifle calibers above .50 are regulated by NFA.

However, there are some hunting weapons exemptions, and .577 Tyrannosaur is one of them. It has sporting exemption though the authorities classify it as a destructive device as per the NFA weapon restrictions. This provision is as per the California law, and hence you won’t need a tax stamp. However, any weapon that’s over 50 calibers and isn’t classified as a hunting weapon is illegal.

Is the .577 Tyrannosaur the Hardest Kicking Round?

The high amount of recoil energy makes this rifle cartridge no joke. It delivers up to 172 foot-pounds of recoil, which makes it hard to shoot and still maintain accuracy. The .577 Tyrannosaur round is pretty hard to shoot, although there are other close competitors such as the .700 Holland & Holland, which offers 160 foot-pounds. The .50 BMG also offers stunning recoil force, which is very close to the .577 T-Rex. Most .50s are fitted with a big clamshell muzzle brake to counter the recoiling effect.

Is the .577 tyrannosaur Ideal for Hunting?

If you chamber it in a light gun, it is quite impossible to make an accurate shot. The amount of recoil is too high to bear. The original rifle for this round was 13-pound bolt action. It wasn’t a gun for hunting but a weapon to counter charging big game animals. If you’ve to use it for hunting, you’d need to be at close range for you to land an accurate shot. It is quite dangerous to hunt at a very close range, especially when dealing with menacing game animals.

Could a.577 Tyrannosaur Kill an Actual T-Rex?

The round can kill a charging elephant if you land your shot correctly on the body’s vital parts. And focusing on the power that this round offers, then the T-Rex is no match.


The .577 T-REX is indeed a hard-kicking round of all times. Although it’s hard to hunt with it, it possesses sufficient power to crumble the biggest game animals. There are some state of the art rounds that offer more applicability, but the .577 T-REX is irreplaceable. 

It is also fun to shoot and feel the massive recoil that can easily make you topple if you’re not careful. Also, you can enhance your ability of landing shots regardless of the recoil the gun provides.

Amazon and the Amazon logo are trademarks of Amazon.com, Inc, or its affiliates.

Scroll to Top