We’re starting a new project here: The Great GunAmerica Ammo Adventure. Each week, we’ll take an in depth look at a specific cartridge. Not a brand, but a specific brand, model, caliber and loading. Ammo performance is a tricky subject, and just because brand “Mega-Doom Blaster Expander” works great in the 9mm +P loading doesn’t mean that the .45 ACP ++++P+++++++ load works properly. With that said, we’ll take an in-depth look at velocity, consistency and performance in ballistic gelatin where appropriate. Want to see your favorite load in an upcoming weekly installment? Let us know in the comments…
There’s not much that the Sig Sauer folks aren’t making these days, except, perhaps shotguns. I’m guessing that’s only a matter of time. One of the relatively new projects from the Sig Sauer team is a line of premium ammunition. Given the recent launch of the new MCX rifles in 300 Blackout, it follows that one of the first ammo offerings would be in that caliber.
I got my hands on several boxes of the Sig Sauer 300 AAC Blackout Match Grade cartridges. The first 300 Blackout offering from Sig is subsonic and makes use of Sierra’s 220 grain Matchking projectiles. Rated at 1,000 feet per second at the muzzle, it delivers 488 foot-pounds of muzzle energy.
In terms of velocity, the marketing folks at Sig hit the nail on the head. The box is marked 1,000 feet per second at the muzzle. I set up a Shooting Chrony Beta Master chronograph 15 feet down range to check out actual velocity out of two different guns.
First, I shot 10-round strings from a Daniel Defense DDM4v5 300 Blackout rifle with a 16-inch barrel. Since this particular ammo is subsonic, I felt it would be tragic not to use a suppressor, so I mounted a SilencerCo Specwar 762 out front. You wanna guess what the 10-shot average velocity was? You got it, exactly 1,000.0 feet per second. My setup measures to 1/10th feet per second velocity and it worked out to exactly, and I mean exactly, 1,000.0 fps. See? There is truth in marketing sometimes. The slowest round I clocked was 961.1 feet per second and the fastest measured 1,022 fps. That gives an extreme spread of 61 feet per second. For you statistics nuts, standard deviation worked out to 19.23.
I also clocked this from a 300 Blackout pistol, in this case, a CMMG Mk 4. Again, given the intended nature of this setup, I used the same SilencerCo Specwar 762 suppressor. Until I got all excited from this subsonic fun and shot the screens off my chronograph, the Sig Sauer 220 grain subsonic load was averaging 888 feet per second from the CMMG pistol with its 10.5-inch barrel.
Accuracy of the round was impressive. Sig refers to this load as match grade ammunition, and the outstanding Sierra Matchking 220 grain projectile is used. Even still, a subsonic 300 blackout bullet flies like a high-speed brick, right on the verge of stability, so tight groups aren’t a given. I fired 5-shot groups with the Daniel Defense DDM4v5, which has proven exceptionally accurate with supersonic 300 AAC Blackout. I set up at 50 yards, which seems to be a very appropriate distance for the subsonic 300 Blackout. The best 5-shot group measured .67-inches while the worst was only .89-inches. From my experience shooting a wide variety of 300 Blackout subsonic ammo, that’s exceptional consistency.
You just know I had to shoot these into gelatin blocks, right? As expected, the started tumbling almost immediately.
While it may sound silly to gel test this round as the Sierra Matchking projectile is not designed to expand, I did it anyway. The theory behind big, heavy, and unstable bullets is that they will immediately start tumbling end over end. What better way to find out than destroying a couple of Clear Ballistics gelatin blocks?
Well, the tumbling theory is correct. As you can see from the photos, the rumbling, tumbling big and heavy Sierra Matchking did a full rotation longitudinally about three inches into the gel. From that point, things got crazy and the bullet followed a curving path, ultimately exiting the gel completely from the side. Fortunately, I had a large backstop and was able to recover one of the projectiles. As you can see, it doesn’t expand (because it’s not supposed to) and it looks fairly pristine. Since the 1 ½-inch long bullet is tumbling end over end, I think the expansion concept is irrelevant in this case anyway.
You can find it for about twenty bucks a box online.