By Matt Sandy
Yes, one other 300 AAC Blackout vs. 5.56 NATO article. However, on this one, I’ll examine the 2 particularly by taking a look at their ballistics. Ballistics is a broad time period that really covers three subsections: Internal ballistics, exterior ballistics. Let’s have a look at all three.
The American-made 300 Blackout was Advanced Armament Corporation’s resolution to the issue, “How do we get 7.62×39 performance in an M4/AR rifle with as little change to said platform as possible?” They began with the 300 Whisper, a wildcat cartridge. They received it standardized and permitted by SAAMI earlier than altering the title to 300 Blackout.
In order to maintain this text at an affordable size, we can be trying on the ballistics by means of a set of pre-determined filters. The major weapon system can be an M4/AR-15 platform with an AAC higher utilizing a 9-inch barrel and pistol size fuel system. I can be evaluating it towards the 5.56 NATO and seven.62×39 Soviet when applicable, because the 300 Blackout is supposed to exchange one and match or surpass the opposite.
Cartridges just like the 6.8 SPC and 6.5 Grendel aren’t applicable comparisons, as a result of they require a unique bolt face and completely different magazines leading to decreased carry capability. By comparability, 300 Blackout solely requires a barrel change. From the navy’s perspective, that’s supreme.
And it’s in all probability a very powerful factor to recollect when taking a look at this cartridge and why it exists. The 300 BLK spherical is a 5.56 alternative, with 7.62×39 capabilities with minimal alterations required for the weapon system. Let’s have a look at how nicely AAC achieved their aim by analyzing its ballistics. I will even give my opinion on the quite simple query, “is it better than 5.56 NATO?”
Let’s dive in.
Internal ballistics covers every part that happens from the second the firing pin ignites the primer till the bullet leaves the muzzle. Maybe probably the most vital utility of that is barrel twist price. In basic, the longer and heavier the bullet is, the tighter the twist price wanted to stabilize it. AAC presents 1:7 in all three of their barrel lengths.
This tells me that AAC, the corporate that has fine-tuned their M4/AR-15 platforms to work with excessive velocity supersonic ammo and low velocity subsonic ammo, deems this probably the most versatile twist price. If, nevertheless, you might be constructing your rifle round a particular bullet weight and cargo, then twist price is a legitimate consideration for optimizing that load. If you’re utilizing lighter bullets a slower twist price can provide higher efficiency.
External ballistics is every part that occurs to the bullet between the muzzle and the goal. Trajectory, wind drift, velocity, and so forth. This is what most individuals consult with after they speak ballistics. The accompanying pictures show multiple completely different frequent loadings of 5.56 NATO, 7.62×39, and 300 BLK.
The knowledge was generated utilizing ballistic coefficients and muzzle velocities primarily from Hornady. I did this for 2 causes.
First, Hornady is a good maker. Second, they listing all the knowledge I must generate the information. The muzzle velocities are an estimate as a result of most revealed velocities use longer barrels like 20 or 24 inches. I subtracted 25 fps per inch till I reached the specified barrel size.
These aren’t presupposed to be laborious numbers, however basic indications of how every cartridge performs. Each cartridge is topic to the identical diploma of error, since I can be doing the identical math for every. Data was generated utilizing the Applied Ballistics cellphone app, at sea degree, on a 70-degree day, 50 % humidity, a 10-mph crosswind for drift in 100-yard increments.
Supersonic Ammunition: I used to be stunned by what the information confirmed right here. Across the board, the 300 BLK rounds have been solely minimally higher if not worse than navy grade 5.56. (NOTE: After reviewing feedback from readers, the writer despatched us up to date supersonic knowledge, proven beneath).
The 5.56 had not less than 500 FPS on the 300 Blackout for velocity, barely decreased muzzle power, rather less than half the bullet drop, and fewer wind drift. And once I say “slightly” decreased power, I’m speaking inside 50 ft/lbs at any distance, with the 5.56 truly outperforming 300 BLK at some.
The 7.62×39 ammunition is mainly an identical to the 300 BLK ammunition. Despite utilizing estimated muzzle velocities, I’m not likely seeing any trace of the 300 BLK rounds being higher by any vital margin, or in any respect. Supersonic 5.56 could be my first selection for longer pictures.
Subsonic Ammunition: Here I included ammunition primarily from Engel Ballistic Research as a result of they listed all the knowledge I wanted for subsonic masses. This is necessary as a result of the Ballistic Coefficient of a bullet modifications relying on the rate. To be particular, the BC will increase because the bullet velocity decreases.
So, utilizing BCs generated from supersonic masses would give us much less correct trajectories than if we used BCs generated from subsonic masses. The 5.56 is the one exception. Atomic ammo doesn’t listing the BC, so I carried over the M855A1 BC. Take that as you’ll. I additionally threw in 9mm and .45 since they’re the first competitors for the subsonic, suppressed position in a brief barrel platform.
The subsonic outcomes have been fairly related to one another.
The 5.56 and 9mm fell quick within the bullet power division by roughly 100-200 ft/lbs throughout the board. This is anticipated, for the reason that bullet weights are practically half that of the others. The .45 had probably the most power on the muzzle however rapidly fell behind as the gap became greater.
The velocities have been extraordinarily shut for all besides the pistol cartridges which completed roughly 200 fps slower than the rifle cartridges. The drop charges have been additionally very related, with the pistols once more underperforming. The 220 gr 30-caliber bullets had the very best general efficiency. The 208 gr Hornady bullet is an odd exception. It had a particularly excessive revealed BC, which causes it to outperform the 220 gr bullets by just a little.
The disparity within the BCs makes me assume that both Engel is underestimating their BC or Hornady is overestimating theirs. Either manner, the 300 BLK takes the win for subsonic masses due to its heavier bullet and higher BC.
Terminal Ballistics is every part that occurs between the bullet hitting its goal and it lastly coming to relaxation. I wish to begin by saying terminal ballistics could be very difficult. There are an enormous variety of elements and variables that may’t be correctly accounted for, and definitely not agreed upon.
There is, nevertheless, one ingredient of bullet wounding that’s universally accepted. When a bullet strikes a physique, it is going to put a gap in that physique barely larger than the diameter of the bullet. By this logic alone, 300 Blackout rounds are higher than 5.56.
Tumbling and fragmentation enhance the dimensions of the wound, however the 300 BLK will all the time have a slight measurement benefit over the 5.56. When evaluating the identical bullet design, M855A1 vs M80A1, the 30-caliber cartridge is superior.
Don’t get me mistaken, each will kill. And the M855A1 positively has superior terminal ballistics to its predecessor, however it could’t outperform the bigger 30-caliber bullets when evaluating related bullet designs.
Both pictures above are from The Wound Channel. The M80A1 picture isn’t as clean, however I feel it nonetheless correctly illustrates the distinction in wound measurement between the 2 rounds. YouTube is filled with ballistic gel check movies exhibiting M855A1 and M80A1 efficiency, together with this video which exhibits the M80A1s effectiveness within the 300 BLK platform.
I haven’t seen any pictures or footage of how the brand new bullets carry out at subsonic velocities, however it’s protected to imagine that at worst, they don’t fragment – which places us proper again originally what place the larger bullet causes the larger wound.
This additionally signifies that, technically, 9mm is best than 300 BLK and .45 is the very best. If solely terminal ballistics have been that easy, or I had extra room to jot down. That being stated, at shut ranges with subsonic loadings, the .30 caliber bullet could also be the only option. It might not put the most important gap within the goal, however it has higher sectional density giving it superior penetration. This will assist it defeat some obstacles whereas sustaining deadly drive higher than the pistol cartridges.
Also, as AAC meant, if the battle abruptly shifts to longer ranges, it positively has superior terminal ballistics at vary. Furthermore, you possibly can throw in a supersonic magazine that overwhelming surpasses the pistol calibers at vary. From a terminal ballistics perspective, the 300 BLK appears to win as a result of its bullet diameter and vary versatility.
I coated lots, and nonetheless solely touched on a variety of the subjects introduced up right here. Especially terminal ballistics. Papers are written on that stuff. But, after trying on the numbers, AAC positively succeeded in seamlessly placing 7.62×39 efficiency into an ordinary AR-15 platform. Is it higher than 5.56? For vary use, I’m going to say no. 5.56 is the most suitable choice for reaching out and touching one thing.
Other than that, I’m leaning in the direction of 300 Blackout as the higher possibility. Especially in an SBR PDW-type position. The 5.56 barely fills that position in a subsonic capability, and 300 BLK has higher accuracy and vary choices than pistol calibers.
I don’t assume 300 BLK replaces 5.56 NATO. The true reply is mission-dependent, however not less than we have now extra viable choices.
Matt beforehand served 5 years within the Army with 2nd Ranger battalion, 75th Ranger Regiment and is presently a gunsmith at The Range at Austin. He additionally competes in each USPSA and PRC matches.