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Rifle Caliber
Aug 14, 2018


Rifle Caliber Smallest to Largest

What Does Caliber Mean?

Caliber is the size of the bullet’s diameter and can be measured in both imperial (inches) and metric (mm) units.  If it doesn’t say mm after, it’s likely in inches (because ‘Murica’).

And for terminology’s sake…a “bullet” is just the metal projectile while the entire thing is called a “cartridge” or “round.”


Parts of a Bullet Cartridge

Rifle Bullet/Cartridge Guide

Rifles and rifle cartridges can do that at ranges that pistols cannot and were never designed to.

The rifle, itself, is only half the equation.  The cartridge is the other half, and when it comes to that other half, you have a number of options.

Shooting squirrels?  You might want something small and accurate.  Shooting xenomorphs?  Probably something bigger.

Here are the definition and units of some of the things we’ll be using to compare the different calibers.

  • Bullet weight: Measured in grains (gr) where 7000 grains      make up a pound…so it’s a really small unit.

  • Velocity: Speed of the bullet in feet/sec

  • Energy: Measured in Joules (J), a rough approximation for      the power of the round




This tiny low-recoiling round is popular for both rifles and pistols.  Called the “twenty-two” long rifle, it’s a “rimfire” cartridge instead of “centerfire” because the firing pin hits the rim of the case instead of…the center.

The .22 long rifle is probably the most popular rifle round out there.

Its small size and high velocity make it ideal for hitting small game like squirrels at range, and its low recoil makes it a great round for beginners and children who want to shoot but don’t want the shoulder bruises that come with a larger round.

Usually reserved for target shooting or small pests, that doesn’t mean it’s not deadly to human targets either.  The small caliber bullets tend to bounce around inside a body and wreak havoc.

  • Bullet Weight: 30-40 gr

  • Velocity: 1200-1600 ft/s

  • Energy: 140-160 J

.30 Carbine


.30 Carbine

Blast to the past!  Not super common nowadays, but it was the ammo for the M1 carbine back in WWII and up to the Korean War.  Pretty low recoil and really fun to shoot in the M1 if you get a chance.

  • Bullet Weight: 110 gr

  • Velocity: 2000 ft/s

  • Energy: 1300 J

.300 BLK


.300 Blackout

The “three-hundred Blackout” is a new round (2011) that aimed to put the larger .30 caliber bullet (such as the AK-47) into the AR platform that normally took .22 caliber bullets.  And also to offer great suppression abilities and the use of current magazines.  Recoil is pretty similar to the regular soft-shooting 5.56x45mm of the AR-15.

  • Bullet Weight: 125 gr

  • Velocity: 2200 ft/s

  • Energy: 1360 




The 7.62x39mm cartridge is a Russian round designed for use in the venerable AK-47 and SKS rifles.  With the importation of these rifles to the U.S., the 7.62x39mm has become a popular round, and some bolt-action rifles, notably from CZ, and semi-autos like the Ruger Mini-30 use it.  The round is large enough for a medium-sized game such as deer and more than adequate for self-defense.  Moderate recoil and moderate range but great knockdown power.

  • Bullet Weight: 123 gr

  • Velocity: 2400 ft/s

  • Energy: 2180 J

  • Price Per Round: ~20 cents

5.56x45mm or .223



The standard caliber of the M-16, M-4, and the civilian AR-15.  5.56x45mm (five-five-six) is the NATO round and is normally loaded a little “hotter” than the civilian .223 (two-two-three) even though the two are dimensionally the same.  Extremely accurate and soft shooting.

Larger than a .22lr, but not by much, many states don’t allow hunters to use .223 on large game like deer because it’s considered inhumane.  It’s used, therefore, more as a varmint round used to kill prairie dogs at long range or predators such as coyotes.

  • Bullet Weight: 55-62 gr

  • Velocity: 3100 ft/s

  • Energy: 1770 J

7.62x51mm or .308



The big brother of the 5.56, the “seven-six-two” NATO round is used by the US military and the .308 “three-oh-eight” is its civilian equivalent.  But this time, the .308 is usually the hotter round.  Much more recoil than the 5.56 but with extended range and knockdown power.  There are very few animals this round won’t take down and it’s also the de facto sniper round the world over.

  • Bullet Weight: 147-175 gr

  • Velocity: 2600-2700 ft/s

  • Energy: 3300-3500J




Russian cartridge that is still in military issue today.  Popular for their sniper rifles, the 7.62 “Russian” (the R actually stands for rimmed and not Russian), is hard hitting with a good amount of recoil.  When you hear this round mentioned, there is one rifle that is always associated with it: the Mosin Nagant.  Surplus makes it cheap to shoot such a large caliber though.

  • Bullet Weight: 150-181 gr

  • Velocity: 2500-2800 ft/s

  • Energy: 3600 J




The .30-06 (thirty-ought-six) began life as the .30 government and was made the primary U.S. military round in 1906 (hence the “06” in the name), replacing the .30-03 round.  Though it was eventually replaced by the 7.62x51mm round in the military after 50+ years, the 06 remains a popular bolt-action hunting round capable of killing any animal in North America given its tremendous knockdown power and range.  With great power comes great recoil, and a pretty steep price per round.

  • Bullet Weight: 150-200 gr

  • Velocity: 2500-2900 ft/s

  • Energy: 2800-3000 J

.50 BMG


Rifle Caliber Smallest to Largest

No rifle caliber guide is complete without the big boy “fifty-cal” BMG (Browning Machine Gun).  It puts everything else to shame with its immense size difference.  Super long range, knockdown ability, and recoil in the form of everything from machine guns to sniper rifles.  If you ever need to take down a T-Rex at 1,500 yards – this is the round you want.

  • Bullet Weight: 647-800 gr

  • Velocity: 2800-3000 ft/s

  • Energy: 18,000 J

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