Blah blah blah... 300 AAC. Blah blah blah 300 Blackout. Blah blah blah 300 Whisper. What is all this talk about this cartridge??? Well, I started to investigate this further and I like what I see.
The 300 Blackout (also known as the 300 AAC Blackout) was "redefined" by a silencer company called Advanced Armament Corp. The goal was to produce a larger caliber bullet that can be fired from a 5.56x45 AR15 platform. This is not new. Many have tried before. Some have just used the AK round (7.62x39) but failed because the ammo is so tapered that it required special magazines or a modified lower receiver to accept AK mags. Also, the bolt carrier needs to be replaced, as well as the buffer and buffer spring. Then there is the 6.8SPC. Same 5.56 magazine but still needed a heavier buffer and spring, new bolt, AND the recoil was MUCH more than the 5.56. In all three system (5.56, 7.62x39, and 6.8SPC) systems, if you choose to shoot subsonic and/or run a suppressor, you will need to change the gas system to be adjustable (or risk failures).
Advanced Armament took the standard 5.56 cartridge, cut it down, and renecked it to accept a 30cal bullet. The dimensions are 7.62x35. This way it uses the same magazine, same bolt, same buffer, and same spring. Basically, the only thing you need to change was the barrel. Great! This caliber also allows you to run subsonic ammo without changing anything!
Since you are running a heavier bullet (110gr -> 220gr) the bullet drop is more, but the trade off is the amount of energy that is retained by the bullet. A better overview can be seen by watching this video
Ironically, this caliber "isn't" new. Advanced Armament really didn't invent something new. What they really did was convince a lot of people (and the military) to seriously look at this for combat effectiveness. Once proven, they spun a very well directed marketing campaign to make this bullet more visible to the world... They marketed it to tactical nuts like me.
The 300 AAC Blackout is pretty much the same as the 300 Whisper. It's wildcat cartridge that was not so popular because due to it's trademark issue. Since Advanced Armament isn't shy about the trademark of this caliber, they pretty much let any manufacturer use it. Because of this, several hundred manufactures have jumped on this bandwagon. From barrel MFGs, scope MFGs, to ammo MFGs, they have lined up to make "something" for this cartridge.
But why? Is it that much better? I'm starting to think so. It's not a long range gun. For the regular folks, it's a 300 yard gun. It can reach out 500+ yards, but its not practical after 500. Either way, it's a gun that packs a LOT more energy than a .223/5.56. When using a 110-125gr bullet, it can take out a deer. It's not intended for big game like elk. It's not really a hunting caliber... unless you are hunting bad guys. When running subsonic with a 220gr bullet it's energy is outstanding for under 100yd and is quieter than a 9mm (suppressed or not). When suppressed, its decibel rating is more like a exaggerated fart.
Cost for ammo is more (when you can find it). $13.00/20rnd of 115gr plinking stuff. $20.00/20rnd for 220gr subsonic. $29.00/20rnd for 110-125gr ballistic tip for hunting. That's pricy compared to $8.00 for 55gr FMJ in .223/5.56.
Finally I had a chance to shoot some 220gr Remington UMC subsonics from a 16" barrel AR. Oh my. The recoil was much less than a .223/5.56 and it knocked the heck out of my steel plate. I was sold. I spent months trying to find ammo. Besides the current ammo shortage, the demand for 300 Blackout ammo has been nuts. Remember the cost? Well, reloading will bring my cost of the 220gr subsonics to under $10.00. Ballistic tips to around $12.00. Now we're cooking with fire! Last month I invested $700 on reloading equipment. This week I built 10.5" 300 Blackout upper for under $400. Yesterday I spent $500 on reloading components.
I'm well vested in this project. Soon, this may be replacing my dedicated 5.56. Next year (when I replenish my toy fund) I'm definitely going to put a suppressor this one and probably use it as a home defense rifle and pig gun. I will also be filing my Form1 with ATF and registering two more AR lowers to be SBR (short barrel rifle) receivers. This way I can have a shorty 300 Blackout, 9mm, and my original 5.56.
For those of you that are still on the fence with your AR build. You can buy a 5.56 upper for $270 from DS Arms. This is NOT a bad choice. It's a proven choice for many years. If you are considering the 300 blackout, check out Model 1 Sales. They offer a 300 Blackout upper for $385, minus the bolt carrier and charging handle. If all you have is a stripped lower, you can buy a kit for $550.