Some re-purpose the AR-15 for big game hunting.
What are the top caliber options for hunting with an AR?
First, lets take a look at all of the caliber options that are available for the AR-15.
AR cartridges that fit .223-length magazines. L-R: .223, .224 Valkyrie, .22 Nosler, 6.5 Grendel, 6.8 Remington SPC, .350 Winchester Legend, .450 Bushmaster
.223 and Variations
The .223 Rem cartridge arrived in 1957, specifically for the new AR-15.
It sent a 55-grain bullet at 3,250 fps from a case a tad longer than the popular .222s.
A lot of ink real and virtual has been spilled over the rounds performance in that conflict.
An all-around cartridge must serve you in an AR that, like this .223, helps you hit from field positions!
NATO approval came in 1980, with a new label: 5.5645 NATO.
A 62-grain boat-tail bullet spun with1-in-7 riflingclocked 3,100 fps and excelled at distance accuracy.
The U.S. Army dubbed this load the M855.
The .223, right, arrived in 1957. The .22 Valkyrie shows current trend to short “fat” cases, long bullets.
Case dimensions for the.223 and 5.5645are the same.
Barrels for the 5.56 commonly get longer throats.
I cant name a cartridge served by a wider range of rifling spin rates!
Positioned between the .308 Win and the .223 Rem, the 6mm ARC offers excellent hunting performance for the AR.
The first .223 barrels rotated bullets 1 turn in 14 inches.
Not long ago I fired an early Remington 40X so rifled.
Solid-copper bullets as light as 62 grains flew wildly and entered targets sideways.
With little enduring support, the 6.8 SPC withered. Sent at 2,625 fps, its .277 bullets kill deer quickly!
They were too long to stabilize with such slow twist.
Nosler advises 1-in-12 for bullets as long as 60-grain Partitions.
A 1-in-8 spin should work with lead-core BTHPs (boat-tail hollow-points) to 80 grains.
Based on the 7.62×39, the 6.5 Grendel (left) outperforms the .223 (right) on deer. Magazines have thin walls.
Now there are friskier .22s for ARs.
Federals .224 Valkyrie, supersonic with 90-grain Sierra bullets to 1,300 yards, is similar.
Both were developed in 2017.
With these 123-grain bullets from 20-inch barrels, the .30 Remington AR clocks 350 fps faster than the 7.62×39.
Beyond 6mm
Bigger bores offer up heavier bullets.
Deer Ive shot with the 6.8 SPC fell quickly dead.
At its 2003 debut, the cartridge used Large Rifle primers.
Straight-case AR rounds, here the .350 Legend and .450 Bushmaster, are now legal for deer hunting in some areas previously designated “shotgun only.”
Small Rifle primers replaced them More uniform ignition!
So, be careful if you are reloading range pick-up brass.
Another 2003 introduction, the 6.5 Grendel, is a necked-down 7.6239, a 1943 Russian Army cartridge.
Tidy groups from Springfield’s SAINT in the light-recoiling .350 Legend bode well for this deer hunter.
Legions of hunters are sold on the Grendels 123-grain bullets at 2,610 fps.
While the Grendel is designed for the AR, the 7.6239 is also available in the AR-15.
Barrels for the 7.6239 are nominally bored .309 or slightly larger.
Are .22-caliber cartridges the best for AR hunting? Only if deer are your biggest game and the rounds are legal in your state.
Hornadys loads launch a 123-grain .310 bullet from a 20-inch barrel at 2,350 fps.
It carries 840 ft-lbs to 200 yards.
In 2011, a competitor appeared and remains very popular today for hunting and sporting applications.
Dwarfed by the .450 Bushmaster, the .300 Blackout (left) is efficient, sends 135-grain bullets at 2,085 fps and offers heavier subsonic loads too.
Mid-weight hunting bullets to 135 grains exit 16-inch barrels at about 2,100.
The300 Blackout cartridge is very popular for hog huntingwhere ranges are typically less than 200 yards.
Additionally, the suppression characteristics of the subsonic loads make hunting hogs with a can quite enjoyable.
Despite its short case, the .450 Bushmaster (left) holds 10 percent more powder than the .243. Warning: it kicks harder.
ensure you read Tom McHales articlecomparing the 300 BLK vs the .223 Rem for hunting.
The .30 Remington AR, developed in 2008, has been largely overlooked.
Its body is over half an inch in diameter and holds 44 grains of water.
Both the .450 Bushmaster (left) and .458 SOCOM (center) pack a lot more wallop than the classic .45-70 Govt (right) loads.
From 24-inch barrels, 125-grain bullets at 2,800 fps carry 19 percent more energy than a .30-30s!
The straight case and .357 bullet of Winchesters .350 Legend make it unique among AR rounds.
A 180 Power-Point at 2,100 fps brings 1,240 ft-lbs to 100 yards.
To bring its rim diameter to the AR-15-friendly .473″ of the Bushmaster, the .458 SOCOM’s (right) is rebated.
Its 22 grains heavier, and more stoutly built, than Winchester JSPs for the .357 Magnum.
The .450 Bushmaster, introduced in 2008, also has a straight case.
Factory-loaded with 250-grain .458 bullets at 2,200 fps, it will take game bigger than deer.
Ballistic Comparisons, AR-15 Commercial Loads
The following ballistic tables were built using factory-provided information.
Not all manufacturers specify test barrel length.
For valid comparisons, velocity data must be adjusted to compensate for barrels of different lengths.
I asked two colleagues with vast experience firing and gunsmithing AR-15s: What if you could have just one… Then: One AR?
What alternate universe are you living in?
Both men conceded a ballistic edge to the 6mm ARC.
But not everywhere is the .223 thought a big game round.
Like other centerfire .22s, its not legal for deer hunting where I live.
The 6.5 Grendel is a hit with hunters around my digs, said David.
Affordable Wolf steel-case ammo gave it a lift.
Those long 110-grain FMJs, with a big air pocket up front, unhinges coyotes.
Hes used bullet of 90 to 144 grains.
Bill Alexander, who developed the Grendel, was right to favor 123s.
Ive never had a 6.5 Grendel that didnt feed perfectly with 6.5 Grendel magazines, Patrick told me.
But I prefer the Blackout.
Very pleasant with subsonic loads.
With 115s it performs like the 7.6239 but taps a much broader range of high-quality bullets.
Hunting regulations matter too.
Need a straight case?
On this list, only the .350 Legend and .450 Bushmaster qualify!
But bullets for the Bushmaster and .458 SOCOM are heavier than needed when not swatting elk or moose.
You get steep arcs and brutal recoil.
Im sweet on the 6mm ARC, perhaps predictably.
Hunting and in competition, bolt rifles were my lot for decades.
I dont use rifles at night and seldom fire them lickety-split.
I dont load them for self-defense.
Cartridge weight matters not in five-round magazines.
The ARC wont trump the Grendel or SPC at the distances Ill fire on deer.
But its efficient bullets will endanger plates too far to smack with its competition.
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