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300 Blackout vs 6.8 SPC

The world of black rifles has been overturned lately, thanks to new rounds coming to market – notably, 6.8 SPC and 300 Blackout (of course!). Both of these heavy-hitting rounds began their lives as oddball wild cats, built in the garages and benches of hunters and veteran shooters. The military caught wind of these ballistic-improved loads and decided to incorporate them into the special operations community. Of course, once something touches the hands of a Frogman or ODA, everyone wants it. But why should you want either? What makes 300 Blackout better than (or perhaps worse than) 6.8 SPC? What’s the true purpose of each round? Let’s find out!

300 Blackout and 6.8 SPC by The Numbers

To figure out where, when, and why you’d want each of these rounds exiting the muzzle of your AR 15, let’s look at their size, ballistics, and grain counts:

6.8mm Remington SPC:

  • Weight (average): 115 grains
  • Velocity (average): 2,500 ft/s
  • Energy (Average): 1,600 lb.-ft.

300 AAC Blackout:

  • Weight (average): Supersonic, 125 grain, Subsonic, 220 grains
  • Velocity (average): Supersonic, 2,215 ft/s, Subsonic, 1,010 ft/s
  • Energy (average): Supersonic, 1,350 lb.-ft., Subsonic, 500 lb.-ft.

Why a 300 Blackout AR 15?

In simple terms, 300 Blackout was designed to provide two applications in one gun: One, the ability to hit far with light loads and respectable ballistics, similar to 5.56 NATO. Two, afford a shooter the ability to go suppressed with nothing more than the change of a magazine and the threading of a can on the muzzle. No other round is capable of doing so while retaining reliable cycling and good ballistics with both loads (super and subsonic).

The creative shooter can easily imagine why the military loves such a round: It gives special operators the opportunity to roll along the mountainsides and hit far and accurate, before moving into Jihad John’s bedroom window in the wee hours, eliminating threats without making a peep – and they can do this all using one rifle.

In the civilian world, 300 Blackout serves a wonderful purpose, too: You have the opportunity to shoot a round with ballistics that are similar to your typical .223s and 5.56 NATOs, while also shooting suppressed to go hunting, enjoy shooting without hearing protection, or just enjoying the cool factor.

Why a 6.8 SPC AR 15?

6.8 SPC was never intended to be quiet, nor was it ever intended to provide dual functions (as a supersonic and suppressed round). The relatively small projectile, while still larger than 5.56, was simply designed to add a little more mass while maintaining the zany velocity that makes .223 and 5.56 hit hard. The end result is a round that performs better at longer distances.

What This All Means for You

So, 300 Blackout has plenty of benefits over 6.8 SPC: It can be supersonic or suppressed without the need to modify your weapon. It can hit hard, quiet and heavy, or it can hit far, fast and zippy. You get to enjoy using standard AR 15 magazines, bolt carriers, and regular ole’ AR 15 upper and lowers – all you need is the appropriate barrel and chamber.

If you’re looking to get marginally better performance beyond, say 500 yards, 6.8 SPC is the way to go. This SOCOM round is great for heavy, static bench guns or long-range hunting rifles. Expect to pay a premium, though – you’re going to need a purpose-designed upper, lower, new internals and a new bolt carrier group.

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. We are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

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