Popular AR Calibers for Deer Hunting By: John McCoy

AR-10 rifle with a scope

Fall is just around the corner. School is back in session, evenings are starting to cool down, and that distinct Fall smell is just slightly in the air. This also means that deer season will soon start. Of course, bowhunters and black powder hunters get first dibs, but centerfire rifle season will be opening soon enough. It’s time to think about dusting off that classic .270, .30-06, or .30-30.

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Or, you could give your AR-15 a go this year. While more and more states are allowing deer hunters to use .223s, we are thinking about calibers that are a little stouter. This isn’t 2005 anymore; there are a bunch of larger-bore, hard-hitting calibers on the market that you can buy either as a whole rifle, or as an upper receiver to simply swap onto your lower. Let’s look at some of the best calibers out there.

Whitetail Whitetail Deer buck - silhouetted in prairie landscape
For years, the Winchester Model 70, Remington 700, Savage Model 10, and others chambers in proven calibers such as .30-06, .30-30, and .308 have ruled the woods. Today’s the AR platform is showing it too has a place in a deer hunter’s hands.

Why Use an AR-15 for Deer Hunting?

A long-time staple of the U.S. military, the AR-pattern rifle, has the distinction of being the longest-tenured service rifle in U.S. military history. It’s been around the block a couple of times. However well the .223 does against enemy combatants, it is unarguably lacking for hunting medium-sized game — especially when you can easily buy a budget rifle from Savage, Mossberg, and a handful of other manufacturers for about the price of an upper receiver.


So why buy another AR-15 or upper?


The AR-15 platform — caliber aside — is an incredible platform to work with. There has never been a weapons system so widely available that is also as modular as the Stoner AR-15 design. The same lower receiver can be paired up with a high-velocity varmint killer (.204 Ruger), or a big bore hog hammer (.50 Beowulf), and a whole lot of in-between.

ARs are a great platform for short- to mid-range deer hunting for a few reasons:

  • Light weight: Some builders have taken ARs well under six pounds.
  • Low recoil: Most of the calibers have extremely low felt recoil, although the big bore calibers (.450 Bushmaster, .458 SOCOM, .50 Beowulf) do hit a lot harder. But the bulk of the deer hunting-oriented calibers have minimal felt recoil. This is a great selling point for young hunters and small-statured hunters.
  • Accuracy: AR-15s are accurate rifles. They are stable, simple to operate, and easy to shoot. Pairing your AR-15 with a high-quality free-floating handguard.

What Are the Rules for Using an AR-15 to Hunt?

The rules are not universal, so you’ll need to check your home state requirements to ensure you are in the right.

Generally speaking, the rules come down to these factors:

  • Bullet diameter/caliber: There are more states okaying the use of .223 for deer hunting.
  • Magazine capacity: Some states have magazine restrictions, so you’ll need a magazine that conforms to any applicable laws.
  • Straight wall cartridges: There are a few states that have opened lands that were once open only to shotguns or muzzleloaders. Michigan, Ohio, Indiana, and Iowa, among others, are allowing straight-walled cartridge calibers, which there are a couple of options in the AR-15 now.
Box of Winchester .450 Bushmaster Deer Season ammunition
Currently, the .450 Bushmaster is arguably the most popular straight-walled deer hunting ammo for AR pattern rifles. The concept of the .450 Bushmaster is credited to Col. Jeff Cooper. Cooper was not only an icon of modern tactical applications. He was a serious hunter too.

Again, we do not and cannot answer the questions about every state. What we can do is strongly suggest that you visit your state’s department of wildlife regulations and ensure you are following all the rules to the letter.

How About Straight-Wall Cartridges?

We talked a little bit about this, but there are now a handful of AR-specific calibers that are larger than usual bores (.350 Legend, .450 Bushmaster) designed for short- to mid-ranged hunts. They are used in similar ways as a muzzleloader or a shotgun with slugs, but in a lightweight and easy-shooting AR-15. Granted, there are a few bolt-action options, but the lion’s share of rifle in .350 Legend are AR-pattern rifles.

Most Popular AR-15 Deer Calibers

There are a few common AR calibers that are better suited for deer hunting than the classic .223/5.56x45mm. Here’s an overview:

Several AR pattern rifles on a table
The versatility of AR Pattern rifles makes it easy to customize the rifle to the shooter and the style of hunting/shooting you want to do.

.300 AAC/Blackout

The .300 Blackout is probably the second most popular caliber for the AR-15 platform. It is designed as a subsonic rifle cartridge to use with a can, and it does it really well. These loads use a heavy 200-plus grain projectile and deliver performance similar to a .45 ACP.

However, the .300 Blackout can also be loaded as a more typical supersonic with deer-specific loads. For instance, the Winchester Deer Season XP packs a 150-grain polymer-tip bullet with ballistics that are only marginally lower than the venerable .30-30 Winchester.

The .300 Blackout is common enough that you can find the ammunition everywhere, and there are dozens upon dozens of complete rifles and upper receivers to choose from. The recoil is negligible making it an ideal first rifle for small and young deer hunters, but they won’t outgrow it anytime soon.

6.8 SPC

While not as popular as the .300 Blackout, the 6.8 SPC represents a good complement to your AR-15 collection. A lighter caliber than the .300 Blackout or the .350 Legend, the 6.8 SPC has a substantially flatter trajectory than these. It gives you an option for a light, nimble rifle that is deadly out to several hundred yards.


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Federal Fusion MSR 6.8
Federal Fusion MSR 6.8

It is important to note that, unlike the .300 Blackout, rifles, and uppers in 6.8 SPC use a different bolt carrier group (BCG) and magazines. The .300 Blackout uses the same BCG and magazines as the standard .223.

6.5 Grendel

Hotter than the 6.8 SPC which is another caliber well suited for suppressed operation, the 6.5 Grendel is a high velocity, medium-range caliber that deploys a roughly .25 bullet. The 6.5 Grendel is well-known as a tack-driving caliber used in precision shooting. However, the .25 caliber, 130-grain slug is no slouch and is certainly capable of dropping a meat doe.


A stalwart of the shooting world, the Russian 7.62x39mm, i.e., the AK-47 and SKS standard, holds its ground just fine in short- to medium-range deer hunting. It does drop off substantially after about 150 yards. However, for short range, it is a serious contender against deer.

Ballistically, the 123-grain bullet is almost identical in muzzle velocity to a 150-grain .30-30, but the energy is a little lower. In the field, though, you can expect it to perform comparably in brushy, short-range hunts.

Red box of Hornady 7.62x39mm SST ammunition
While the 7.63×39 is a .30 caliber round and works well in AR pattern rifles, ensure you select ammunition designed for hunting. Hornady’s SST is a choice that would be hard to beat.

The main advantage of using 7.62x39mm? It is inexpensive, steel-cased target ammunition. With the importation ban of ammunition from Russia, local manufacturers are ramping up production of brass cased 7.63×39. If you already have some AKs in your collection, chances are good that you already have a stockpile of Wolf or PPU laying around. There are plenty of reasonably priced AR-15 rifles in 7.62x39mm, and complete, ready-to-use upper receivers aren’t hard to find, either.

Parting Thoughts

The AR-15 has proven to be utterly versatile, reliable, and easy to use. With little felt recoil and great natural accuracy, it is a natural for hunting duty. However, the .223 is not a natural fit for deer hunting. Thankfully, due to the modularity of the design, there are plenty of options out there for larger calibers that are more than adequate for deer hunting duty. We’ve covered some of the most popular choices, although there are a few more calibers that are worth a look. We are sure you will find whatever you need in our broad selection of AR-15 rifles, uppers, or raw parts to build your own dream rig.

Have you ever used an AR for hunting? What are your favorite AR calibers for deer hunting? Let us know in the comments.

  • Dave Dolbee with a steel target showing bullet impacts at 1,000 yards
  • Several AR pattern rifles on a table
  • Federal Non-Typical ammunition box
  • AR-10 rifle with a scope
  • Box of Winchester .450 Bushmaster Deer Season ammunition