Favorite cartridge for the AR-15, and it's use case.

[adcoch1]

Watching several cartridge comparison discussion threads got me wondering, what is everyone's favorite cartridge for the AR-15, and how do you use it?

I have ar rifles and pistols in 5.56, 300 blackout, 6.5 Grendel, 7.62x39 and 458 socom. Have had a few 9mm and 22lr. I actually like them all, and plan to try out several more if I get the chance!

But I tend to build a use case and then find a cartridge to fit it, so a specific gun has to match the cartridge and the intended use. I also like to build guns, so naturally AR-15s are the easy button. They all seem to look quite different though, which prompts the question which is your favorite in the AR-15?

Mine is probably the 300 blackout, because I use it for SBR and pistol pdw roles. I love supers in it, and a short barrel just doesn't lose much over a long one, plus it's reasonably quiet. And subs are even better, especially with a can. Just a fun little cartridge, like a modern 30 carbine with better bullets!
Second is probably my 458 socom in a 8" upper. So much power in such a small package, built it to replace a saiga shotgun with slugs. It's a blast too!

So what's your favorite?

 

[Anchorite]

223/556. Pigs, coyotes and vermin. Range time for the kids. I’m not into gun games.

 

[rust collector]

223 and 300 BK for me too. I would love to see a 22TCM option for midrange varmints and just fun, but I won't hold my breath. The flexibility of the 300 is fun, and the silencer puts it in a league of its own. 9mm would be fun to shoot, but the format is needlessly bulky for a pistol round.

 

[1948CJ2A]

I own 3 AR platform firearms. (1) AR-15 Colt A-2 style 20" barrel with handle (2) AR-10 PSA .308 Win 18: barrel flattop (3) AR-9 PSA 9mm 10" barrel.

The AR-9 was purchased purely as a self-defense suburban weapon.
The AR-10 was purchased for plinking and pig hunting.
The AR-15 was purchased for plinking.

I'm not an "AR Guy" but I appreciate them and have fun with them on occasion. I would have to say the AR-15 setup I have, which is essentially like a civilian M16, is my favorite in terms of shooting and having fun with. I don't hunt with it but its cheap and fun to shoot.

 

[Rexster]

.223/5.56 for general utility, in 16” and 18” barrels lengths, though I consider the AR15/M4 to be a “reserve” weapon, stored away; not kept for reaction to a defensive situation, because the safety/selector is oriented downward when ready to fire, which conflicts with weapons on which I have FAR more training reps*. Other family/household members, who do not have other weapons’ safety/selector systems hard-wired into their conditioned reflexes, would be more likely than me to use an AR15/M4, in a situation that called for everyone to grab a long gun, while I would have my hands on either a shotgun, or a manually-operated rifle chambered for a larger bore.

300 BLK for a legal handgun, with a LAW folder, which makes it legal, in more places, to keep with a loaded magazine inserted, while being transported in a vehicle. 300 BLK is more efficient, and a bit less loud, when used in shorter-barreled weapons, compared to .223/5.56 NATO. I think that my wife likes the idea of a 300 BLK “handgun” more than I do, but that is OK; she can be the gunner, as necessary, while, ideally, I use my past pursuit driving driving training to evade the situation, using 5.7L of V8.

The idea of adding more cartridges, for our AR15/M4 weapons, does not appeal to me. Keeping .223/5.56 and 300 BLK mags segregated seems difficult enough, already.

*I might well try to commit to a truly serious re-training effort, this year, to become more comfortable with the AR15/M4 safety/selector lever. This might well include keeping one weapon set up as a dedicated “dry” training weapon, well-marked as such, to be aimed at “target” fully capable of stopping an errantly-loaded live round.

 

[someguy2800]

I use 300 blackout for self defense and shooting games, 5.56 for varmints and longer range plinking, 7.62x39 for plinking, and I have suppressed 22lr and 9mm. I would say my favorite I’ve had is my 358 yeti. I used it for deer hunting to great affect. I recently sold that to another forum member to build a ruger SFAR in 375 raptor. I also have a 350 legend and 45 raptor.

The Yeti is seen here along with a 7.62x39, 444 marlin, and 25/06



My suppressed 9mm gets the most rounds out of any of them. Since I don’t have the Yeti anymore I suppose I can’t pick that. When Russian X39 ammo was $4/20 I would have picked that.

In todays market 300 blackout is probably my favorite. It’s by far the most pleasant to shoot of the rifle calibers I have.

 

[adcoch1]

I use 300 blackout for self defense and shooting games, 5.56 for varmints and longer range plinking, 7.62x39 for plinking, and I have suppressed 22lr and 9mm. I would say my favorite I’ve had is my 358 yeti. I used it for deer hunting to great affect. I recently sold that to another forum member to build a ruger SFAR in 375 raptor.

Seen here along with a 7.62x39, 444 marlin, and 25/06

View attachment 1191653

Still on my list to get a yeti, one of these days...

 

[someguy2800]

Still on my list to get a yeti, one of these days...

It’s cool, I should have kept mine but I’m trying to trim down on stuff and already have 3 35 Remingtons and my upcoming 375 build

 

[earlthegoat2]

450 bushmaster is my most used. Deer, pigs, and whatever else legal walks in front of me during those times.

6.8 SPC for the same but I also use it more specifically for coyotes.

224 Valkyrie for a predator and varmint rifle that can also be used for deer in a pinch with 90 gr Fusions.

I also have uppers in 458 Socom, 50 Beowulf, 350 Legend, 22 Nosler, and 204 Ruger that I like to have but really don’t mess with.

I have my SP-1 Carbine clone build rifle as my sole 223/5.56 rifle just because.

 

[Lo-Profile]

Have rifles and pistols in 5.56, 300 Blackout and .308
Rifles only in 350 Legend and 450 Bushmaster
CMMG conversion kit for 22lr in a KAK 4.5" barreled pistol

 

[marksman13]

6.8 SPC and I use it for pig hunting and as a general purpose rifle that rides in my truck just in case. I honestly feel like it is the perfect AR-15 cartridge. Others disagree.

 

[Legionnaire]

I’ve never been much of an AR guy though I’ve owned several in 5.56 over the years. More recently I’ve built one in 6.5 Grendel and one in 6mm ARC, both of which I enjoy more than the 5.56. I guess my favorite is the 6 ARC, which is a great cartridge for steel at distance. I’m also hoping to use it for varmints.

 

[troy fairweather]

6mmarc.

 

[mcb]

22LR, I have a dedicated upper that has been very reliable after a bit of break in. Mostly for plinking fun.
223/556, most used for gun games like carbine matches and 3-gun matches.
300 Blackout, Both pistol and carbine and I love this cartridge as a subsonic cartridge. My general truck/UTV/tractor gun is usually one of my 300 BO's.
30 Remington AR, because I like really odd ball cartridges. Brings nearly but not quite 308 Winchester performance to the AR-15 lower. The upper is very proprietary.
450 Bushmaster, I like short fat slow cartridges. Works great on deer and you should see what it does to Raccoons and Armadillos.

 

[ECVMatt]

5.56/.223 because I shoot and hunt in open spaces and the cartridge just plain works. I can't even begin to count the number of things I have dropped with it. Deer, pigs, coyotes, bobcats, and all types of lesser varmints. It may not always be the optimal choice, but if you can get a good hit at a reasonable range, the game is over. I pretty much used it daily in Texas for about 3 years and we became good friends.

Now I have tons of components and just enjoy shooting it. I have a few bolt actions and a few more AR's.I can't see getting started on a new cartridge at this point.

 

[LoonWulf]

223/556 wins the practicality race imo.......but if were talking favorite? The .458 is head and shoulders my favorite.
I dont generally have a use case for an AR besides fun.

 

[cfullgraf]

I like the AR-15 concept although it is a bit light for many applications.

I have AR-15 rifles chambered in 17 Rem, 204 Ruger, 223 Rem, 22x6.8, 22 Nosler, 6x45, 6.5 Grendl, 6.8 SPC and 300 Blackout.

I feel the performance drops off with the 6mm, 6.5 mm an 6.8 mm ammunition. Maybe they work fine for the military.

I like 300 Blackout as it s a good short range defense cartridge, 100 yards or so, with minimal collateral damage down range. I guess the 6mm and 6.5/6.8 mm cartridges could be considered similarly.

I have one 17 Rem AR-15 plus a bolt 17 Rem. If I was into pelt gathering, they would be good but their range is limited as compared to 204 Ruger or 223 Rem.

I shot Service Rifle competition for a while wih a Colt Match Target and CMP/Compass Lake Service rifle competition rifle. Both great rifles.

My main prairie dog rifle AR-15 with a 26" heavy barrel chambered in 204 Ruger. It shoots a bit flatter out to longer ranges (600+ yards or so) than 223 Remington. Less twisting on the scope knobs.

 

[DMW1116]

I'm still running with the standard 5.56/223 chamberings. Mine are 99% range toys/target guns. The 223 is accurate enough to keep things interesting, and cheap enough to keep them frequent. I considered a 300 BO or 450 BM for a while, but those are considerably more expensive to shoot. If I hunted or had some other frequent and serious endeavor, then a 450 BM or 458 Socom would be more appealing.

 

[hoardingthemanual]

Primal Rights has me sold on the 22 ARC in the AR15. Use? Just holes in paper. Might sell some redundant guns and jump on one.

 

[MarshallDodge]

5.56

It is what the gun was designed for
Cheap to shoot
Low recoil
Targets to 600 yards and beyond
Varmint and medium game capable
Tons of free brass available and low cost to reload

 

[Phaedrus/69]

My ARs tend to kept for plinking and home defense. I'll note that I have not hunted in a long while so at the moment hunting performance isn't relevant for me. My favorite AR round is the .300 Blackout. Nothing wrong with the 5.56, I still have three rifles in 5.56/.223 Wylde. But the .300 AAC is cheap to shoot, the muzzle blast is much less severe and it's fun on targets. Shooting steel or other heavier targets the momentum difference is easy to see, and when shooting paper a .30 cal bullet makes leaves a hole that's easier to see vs a .22 cal bullet. Fortunately I've never had to use a rifle (or any gun) for self defense but I'm pretty confident that bullets in the 110gr-125gr would do the job adequately.

 

[greyling22]

I have uppers in 223, 9mm, 300blk, 300 hamm'r, 6.5grendel.

sold the blackout and i felt it was anemic in SBR form.
never shoot the 223
shoot the 9mm some when I just want to plink, but usually I plink with other platforms.

I've about decided the AR is just a hunting rig for me. I'm not a big hunter, and I'm not confident in my shot placement to use a 223.
I built the 6.5 grendel as an antelope gun. I rather like it, and it performed well in that capacity (shots out to 300yds) but then I lost access to that hunting spot.
I built the ham'r as a pig gun to replace the blackout. More punch out of an SBR. Realistically I should have just gotten another grendel upper, but I wanted to have an easier source of brass. I shot a deer with it, then lost access to the pig hunting property (friend sold it) before I could put it into service in that capacity. Oh well. maybe I'll find a new place some day.

 

[Armored farmer]

5.56

I had to get rid of my AR.... but I had a 5.56 with a reflex sight and a cmmg 22lr conversion kit. The conversion kit wasn't perfect but I'd say 98% with quality ammo. It was a fun plinker and also a capable farm defender in 5.56.
I also took a few pigs with that 5.56 down in TX.

 

[Captains1911]

My favorite cartridge for the AR-15 is 5.56mm and my favorite for the AR-10 is .308 Win.

 

[bangswitch]

Watching several cartridge comparison discussion threads got me wondering, what is everyone's favorite cartridge for the AR-15, and how do you use it?

I have ar rifles and pistols in 5.56, 300 blackout, 6.5 Grendel, 7.62x39 and 458 socom. Have had a few 9mm and 22lr. I actually like them all, and plan to try out several more if I get the chance!

Mine is probably the 300 blackout, because I use it for SBR and pistol pdw roles. I love supers in it, and a short barrel just doesn't lose much over a long one, plus it's reasonably quiet. And subs are even better, especially with a can. Just a fun little cartridge, like a modern 30 carbine with better bullets!
Second is probably my 458 socom in a 8" upper. So much power in such a small package, built it to replace a saiga shotgun with slugs. It's a blast too!

So what's your favorite?

What's your purpose for the Grendel?

The only two AR's I have are .300 BLK and 6.5 Grendel. I couldn't say which is my favorite, they have very different focuses. I built the 16" Blackout for CQB and it's a great round out to about 200 yards. I built my 20" Grendel for long range, and it works to a little past 1000 yards. The two uppers share a common lower.