Awhile back we showed you some pictures of the Barnes sent us of their 300 AAC Blackout 110 grain ammo. Photos are nice, but nothing beats getting hands-on and running our own tests. 300BLK has been talked about quite a bit since we first announced it back in 2010, and more companies have jumped on this caliber than any other I can remember with the exception of the .40. What has been lacking up to this point is a performance round which will expand as needed, and retain its mass through barriers. I have nothing against tight groups at distance, but for a caliber which is best at 300 yards and in, I'm interested in how quickly it can put a beast down. Since most deer aren't hiding behind windshields or walls, you can surmise the two legged predator is the focus of this cartridge.
Click the image to jump ahead to the rest of the article.
more
I make no claims of having the level of knowledge approaching that of subject matter experts such as Dr. Gary Roberts, but we can all understand why we want a round that comes to a stop inside a body instead of continuing out the other side. Consider the energy involved, and look at it this way. Hold your hand up in the air, and hit your finger with a hammer. Then put your hand flat on the floor, and hit your finger just as hard. In both cases the energy applied is the same, but its obvious which one is going to hurt worse. This is an obviously simplified explanation, but it gets the point across.
So, we see that full energy dissipation within the target is important. This feat of physics is performed by using bullet expansion to limit penetration. In the case of the Barnes 110 grain TAC-TX bullet, the expendable polymer tip allows for smooth feeding, which is particularly important in magazine fed actions, and after impact it is gone in short order. Along with expansion and preventing over-penetration, the bullet also needs to retain mass while overcoming barriers, and some barriers are more difficult to deal with than others. In general, heavy glass like that found in windshields tends to be one of the most brutal tests on ammunition. The hard glass has no give, and often shatters bullets resulting in a highly reduced mass striking the target, or in many cases, just fragmenting upon exiting the glass and showering the target with bits of shrapnel.
We had several recent opportunities to do ballistic gelatin shoots with a few larger ammunition companies while doing work on law enforcement ranges. All of the companies use the same standardized testing; the gel is calibrated by shooting the block with a BB to confirm velocity and penetration are within testing parameters. Comparing the larger, slower 7.62mm Barnes bullet to the range of smaller and faster .223/5.56mm LE offerings is apples to oranges, but the results were still notable.
One of the best performing LE .223 loads we've seen is the Remington 62 grain Premier Core-Lokt Ultra Bonded PSP, which retained 31.5 grains with 12" of gel penetration through auto glass. Without the glass, the round held 61.1gr in bare gel. By comparison, the 300BLK Barnes 110 grain TAC-TX (lot A53) results weighed between 96.1 and 100.4 grains after defeating the same glass barrier. Shooting bare gel, without any barrier, recovered 110gr 300BLK Barnes varied between 108.2 and 109.1 grains.
Is the Barnes bullet perfect? No, though within the limitations of the 300BLK caliber it does appear to do very well. Dr. Roberts points out in a recent paper of his that ideal penetration for LE applications is between 12-18" in gelatin, and the Barnes seems to be coming in several inches deeper depending upon what barriers it is fired through. For military applications or hunting , the increased penetration doesn't typically have the same concerns that domestic LE work deals with, so as with all things, the intended application will dictate what is acceptable.
Take this all with a grain of salt, as the 5.56mm M4 you carry around now isn't going anywhere for a very long time. I'll also point out the image showing the gel has been toned to show the gel and bullet impact more clearly. Nothing was done to alter the content of the image itself, and the large wound cavity shown is the same as the original picture, just darkened a bit to show it clearer.
[nggallery id=549]
