The house is on fire and you only have time to grab one AR-15.
This is just a thought exercise and your answer can be very, very different from mine.
We should probably start of by looking at what is available.
I will make this list much shorter than it can be and only count the calibers I own, not all possible options (read as almost half all available non-magnum calibers).
That gives me a good spread of choices and covers all of the most popular options.
I have been really jonesing for an AR in 10mm and Quarter Circle may be making one I like, but up to now most of the options have been direct blowback and that isn’t my favorite.
Of these, the short-range options are immediately off the table.
I know .300 BLK is awesome and great for suppressed use, as are the .458 SOCOM, 9mm (especially with Seismic 185-grain bullets) and .45 ACP.
The thing is, if I only have one AR it needs to do more than just CQB work with a suppressor attached.
The .22 LR option goes away as well. The round is awesome fun and death on bunnies and squirrels, but that is a rather limited role too.
The awesomeness of the 6mm FatRat is sending 100+ grain bullets down range at +2,800 fps.
The disadvantage is it is a true wildcat and has ZERO factory support.
I may end up getting a 6mm ARC just to have something similar in factory trim, but even then it wouldn’t be my only AR.
That leaves us with 5.56 NATO/.223 Rem, .223 Wylde or 6.5 Grendel for my one AR-15.
The .223 Wylde may not count as a distinct chambering for some of you, but in a precision rifle it sure should be.
Although I really like the 6.5 Grendel and it is more damage/distant capable, the ammo supply factor nudges it out of the running.
This means the much better designed chamber of the .223 Wylde wins out for me.
It can shoot standard 5.56 or .223 and with proper ammo gives a precision advantage the other two do not.
Without getting into brand-specific wars on if Aero Precision, Anderson, Spikes Tactical, KE Arms… uppers and lowers are the best, let’s look at the do-it-all functionality of some setups.
My White Oaks Armament 24-inch upper is a superb piece of kit, but it is huge and heavy and is a poor choice if I am not using it in its designated role of sending 75+ grain bullets long distances.
It is a fairly inexpensive method to practice for long-range shooting and is even better for learning by failure at wind reading, but it is not the best all-around choice.
Several of my guns run a fairly lightweight 16-inch carbine setup.
Even the quad-rail versions are just too short for great velocity and can’t reliably reach very far.
That leaves my 20-inch heavy-barrel quad-rail gun for my one AR-15.
She runs the .223 Wylde chamber, is super accurate and provides a significant velocity gain over any of her 16-inch siblings and the thicker barrel provides much more rigidity and thermal regulation even with prolonged rapid firing.
It helps that this is my 3-Gun primary, so I have a lot of time running her and the Geissele SSA-E trigger is my go-to.
That trigger is perhaps a bit slower on the close work than my Geissele 3-Gun trigger, but the two-stage SSA-E is so much better on the 200-yarders thrown into some go-fast stages.
The SilencerCo muzzle brake does increase the noise quotient quite a bit, but it is effective at mitigating muzzle rise and gives the option of adding the Omega can.
I have run that setup a few times in matches just because, and it works great.
It also confuses the people in the other heats, as to what I am shooting and why it sounds weird.
Mine is set up with a Magpul ACS stock, which works well for me.
I like the storage for backup batteries, a very basic cleaning kit and the simple flexibility of LOP adjustments for when I am wearing armor or not.
The GunSkin wrap doesn’t just make it better looking and express my personality, it also helps to protect the anodizing from 3-Gun’s wear and tear.
Conclusion: If I Could Only Have One AR-15
In summation, at one end of the extreme, I could run one of my braced pistols with a 14.5-inch or shorter barrel, but that gives up too much for an all-in-one.
At the other end, my 24-inch barrel precision rifle is the most accurate AR I have, but it is long, clunky and heavy, and really gives up too much in the other direction.
My 20-inch 3-Gun rifle was set up for CQB work with offset irons and a Swampfox Arrowhead 1x6x24 scope to extend out.
For close work, it lives at 1.5X so I can still run that with both eyes open.
For the 200+ yard tangos, the 6X setting brings the target close and clear, but still retains a steady image.
With the 20-inch heavy barrel, velocity is very good if I need to stretch out to 400 yards and long shot strings don’t deviate from heat buildup.
I realize that I am biased as it is the AR I have the most time behind.
It is also comforting as I know in 6000+ rounds the only mishaps have been user-induced. Reliability is a very solid plus in an “only one” scenario.
What’s your pick for AR-15 if you could only choose one? Let us know in the comments below!