What's the best alternative to 5.56 for an AR-15?

[Echo40]

So, upon being thoroughly educated that .223/5.56 is in fact a Varmint Cartridge, I've found myself seeking an alternative chambering which may be better suited for general purposes including Big Game Hunting as well as Personal Protection, preferably one which an existing AR-15 can be converted to with a simple swap of the Upper.

However, there are so many choices available that it has my head spinning, so I thought it would be best to take it to the experts and get your insight on the subject.

So what in your opinion is the optimal chambering for an AR-15?

 

[IAM Rand]

Kind of a loaded question so to speak. Anything can be a varmint cartridge. You have to look at cost and availability of ammo/brass/bullets.

I have a 6ARC that I am hoping to take a deer with this year. Got it on a whim but, have grown to really like it. Using an 85gr Lehigh Controlled Chaos and Benchmark powder. Only going 2600 FPS +/- but, it is fun to shoot. I am using a CMMG and a Burris scope. I customed the load so the 2600FPS is giving me sub MOA at 100yrds.

I was able to get a bunch of ammo included with the purchase of the CMMG so all I had to do was shoot the over the counter Hornady and then find a good load. some of the other calibers might be easier to find but, might be more expensive.

 

[STORMINORMAN]

"General Purpose" = 300 Blackout, IMHO...

Cheers!

 

[LVSteve]

Not sure what the OP considers "Big Game". While I believe you could reasonably use all of the above on Whitetail Deer, it gets iffy using a number of those cartridges on anything bigger, say Mule Deer or Elk. A lot also depends on what state he is in and the expected shot distance.

For self defense, 300 Blackout is a good compromise when it comes to hitting power and capacity, and gives you the flexibility to go subsonic and suppressed.

 

[NewLiberty]

This is a "purpose driven" decision. What do you consider "big-game"? Are we talking deer and hogs, or bears and elk?

What is the longest distance you plan to shoot game with it? .300 blackout and .350 Legend are good within a couple hundred yards, but both drop pretty quickly after that.

6.5 Grendel is a great longer distance cartridge, but ammo can be hard to find.

 

[DeplorabusUnum]

By general purpose I assume you want one weapon to defend your castle, get rid of pesky varmints, put meat on your table, and enjoy shooting at the range for fun. I'd pick 300 Blackout of those listed based on availability alone. Everyone has this round in stock

 

[STORMINORMAN]

P.S. With the possible exception of 7.62x39, 300 Blackout has far the best selection & availability for factory ammunition choices...

Reloading is also much more "user friendly" as brass & bullets are widely available.

 

[Dave Lively]

I voted 300 Blackout but unless you are going to use it for hunting would stick with 5.56/223 for an AR. They were designed for 5.56 and I have always had the best results buying guns in the caliber they were designed for.

My experience with 45 ACP 1911s has been very positive, 10mm and other calibers not so much. Same goes with 9mm guns rechambered for 40 S&W when it first became popular. That's not to say such guns cannot be reliable, they just don't have the long track record of a 5.56 AR.

The 300 BO isn't much more powerful than 5.56 but offers the ability to shoot heavier and bigger bullets. I am not a hunter so I will leave how much that helps with hunting to those that have actual experience except to note it would be legal in states with some sort of .243/1000 ft-lbs lower limit for hunting cartridges.

If you want 7.62x39 consider getting an AK style rifle.

If hunting is a theoretical consideration and your main use will be personal protection don't worry too much about 5.56 being considered a varmint cartridge. A lot of the concerns about how well it will perform in that role have to due with how it performs at 100+ yards which isn't much of a concern for most self defense situations. The ammo is less expensive and any rifle round will be much more effective than handgun calibers.

 

[Buick]

I'd be looking at an AR10 if large game is on the menu.

 

[rockquarry]

If you're looking for an alternative cartridge in an AR, you'll be limiting yourself to those cartridges with dimensions that will fit in the framework of an AR. Maybe it would be best to consider a bolt-action design where there are no such limitations and cartridges with much better performance can be used.

 

[wood714]

So, upon being thoroughly educated that .223/5.56 is in fact a Varmint Cartridge

The souls of a few people in the SE Asia area thought it was a good round.

Déjà vu?

 

[Rpg]

I’ve never thought the 223 or its nato equivalent an adequate big game cartridge. They’re fine for coyotes but not for our Mule deer, elk or black bear.

Likewise, I don’t like the AR platform well enough to buy one. Here in Colorado, you can’t hunt big game with a rifle that holds more than 5 rounds. The AR platform creates problems shooting from prone (the pistol grip won’t let you get low enough to the ground).

If I was in the market for one rifle for home defense and big game hunting, I’d be unlikely to buy an AR. I’d be much happier with a bolt action rifle in 30-06 or a lever action in 30-30.

 

[Mike SC Hunter]

In free states I don't understand why anyone would use the weenie 300 blackout or 9mm legend.......Lots better cartridges avail for an AR. My favorite AR Hunting cartridge is the 7.62x39. Using Hornady SST ammunition I have killed 14 deer with it in the 22-23 seasons.

 

[Well Armed]

300 blk is basically a pistols round made to shoot out of an 223/556 AR mag with a short barrel AR15 subsonicly. If I have to grab a rifle I want rifle ballistics with rifle damage. 300blk ain't it.

 

[STORMINORMAN]

In free states I don't understand why anyone would use the weenie 300 blackout or 9mm legend.......Lots better cartridges avail for an AR. My favorite AR Hunting cartridge is the 7.62x39. Using Hornady SST ammunition I have killed 14 deer with it in the 22-23 seasons.

What about those other three that you could POTENTIALLY harvest...?

Cheers!

 

[Valmet]

.308 hands down. Versatile, available, affordable…

 

[STORMINORMAN]

.308 hands down. Versatile, available, affordable…

Uh, the OP said "... for an AR-15?"...

Cheers!

 

[Valmet]

Uh, the OP said "... for an AR-15?"...

Cheers!

I understand that- but IMO I’d easily trade a pound or two for real versatility of .308 (not 7.62x39 vs .300 Blk). The pros far outweigh the cons for a cartridge like the .308 that can do almost anything.

ETA- I guess I’d the options I’d go for 7.62x39 simply because of availability.

 

[alwslate]

The 7.62X39 is fully equal to the 30-30. Even betters it out at 100 yds because it uses pointed bullets that retain velocity much better. No body complains about the 30-30 as a deer ctg.

 

[rockquarry]

The 7.62X39 is fully equal to the 30-30. Even betters it out at 100 yds because it uses pointed bullets that retain velocity much better. No body complains about the 30-30 as a deer ctg.

Maybe not fully equal to the .30-30, but close. You're right, no one complains about the .30-30 as a deer cartridge because they accept it for the short-to- medium range cartridge it is. Spitzer bullet or not, the 7.62x39 is not a long range cartridge either, just like the .30-30.