With so many different loads available in 300 Blackout, many folks are left wondering: Just how far out can one push his or 300 BLK-chambered AR 15? At what distance does the chance of ringing steel become pure chance? The answer to that question, again, varies wildly – will you be shooting unsuppressed supersonic or subsonic, or suppressed supersonic or subsonic? Rifle, SBR, or pistol? Plenty of factors are at play here, so let’s dive into it.
300 BLK Supersonic Max Effective Range
First thing’s first: The “official” maximum effective range of a 125-grain supersonic 300 Blackout round, fired from a 16” barrel, is said to be 460 meters. So that’s it, right? Wrong. If you’re like many AR owners, this would be your last stop. But if you’re reading this, you’re likely willing to push the limits. So just how far can one truly push 300 Blackout?
To figure this out, we have to crunch some numbers of another popular, intermediate cartridge that can push out pretty far: The venerable 7.62x51mm, fired from your military equivalent rifle, The M-110C by Knight’s Armament. This AR 15 platform and .30 caliber round are most similar to any 300 Blackout AR 15 rifle. It sports a 20” barrel – not outside of the realm of normalcy for a 300 Blackout – and it functions generally the same as any other AR 15.
Comparing to “that other” .30 Caliber AR round
The .308 cartridge fired from this rifle boasts a max effective range of 800 meters. When we compare the ballistic events of the two, we can find the real max effective range of 300 Blackout. With a 175-grain .308 cartridge, the M-110C manages a ballistic coefficient (hit probability) of around 50% at 800 meters when supersonic.
With the M-110C hitting 800 meters, the .308 gives up 335” of drop and 81” of crosswind deflection at around 10 mph, pretty common conditions. This is the data that dictates the .308 is at its max effective range – any amount of drop or crosswind deflection beyond this, and hit probability become unreliable.
Levelling the Playing Field
So, with these conditions dictating max effective range, how far out can we push a 300 Blackout (supersonic) cartridge before we achieve similar ballistic data? Well, with a 20” barrel at 670 meters, 300 Blackout drops 355”, but at 600 meters, it gives up 81” of crosswind deflection. Average these two numbers, and you’re left with a max effective range of 648 meters.
What You Need to Hit 650 Meters
Of course, this range is achieved using a particular (and slightly uncommon) 110-grain round with a polymer tip and boat tail profile. With this grain, a 1:10 twist rate is also recommended instead of your common 1:7 or 1:8 twist rates. To be sure, shooting 300 Blackout this far means you’re not going to be building an AR 15 that’s as capable of shooting subsonic loads at distance unless you invest in a second 300 Blackout barrel assembly and a Dolos QD Barrel System for easy swapping.
But there you have it: 300 Blackout, when fired using a 110-grain cartridge in a supersonic load, will punch out to about 650 meters. For those of you who are unaware, the max effective range of a common 5.56 NATO is around 600 meters. So, with a little magic, you can best the AR 15’s gold standard of munitions while still enjoying a very cool, heavy, more powerful round.