What is the purpose of .300 Blackout (often written as 300 BLK) and why would somebody use this caliber over a standard .223 or 5.56x45 rifle? 

Part of the gun community thinks this is a fad round that will go the route of extinction. But I think 300 BLK excels in some areas and suffers in others. No, just having the Honey Badger in a video game doesn't count. 


I own rifles in both calibers. In fact, my first AR-15 rifle build was in 300 Blackout with a 9-inch BCM upper. Here are some reasons why someone might choose .300 Blackout over 5.56mm:

1– AR-15 Compatibility: .300 Blackout was designed to be compatible with the AR-15 platform and it uses the same magazines and bolt carrier group as the standard 5.56mm NATO. This makes it easier for users to convert their existing AR-15 rifles to .300 Blackout by just swapping out the upper receiver. 

2– Ballistic Performance: .300 Blackout typically offers better performance at shorter ranges compared to 5.56mm and it was designed to provide similar ballistics to the larger 7.62x39mm cartridge. 

3– Subsonic Capability: One of the significant advantages of .300 Blackout is its ability to be used with both supersonic and subsonic ammunition. Subsonic rounds are quieter and can be used very effectively with suppressors. Where .300 Blackout shines is for those prioritizing stealth and reduced noise signature. The subsonic rounds in closer quarters also out outshine something like a 9mm sub gun but come in a similar package. 

4– Versatility: The .300 Blackout cartridge is versatile and I think *best* suited for short-barreled rifles when compared to 5.56. You have a myriad of 5-9 inch 300 BLK guns on the market. This compact package opens up opportunities for a dedicated truck or backpack gun for instance. 5.56 rifles suffer from reduced effectiveness with very short barrels due to incomplete powder burn.

5– Hunting and Defense: In terms of hunting, .300 Blackout is often preferred for hunting medium-sized game at closer ranges due to its better ballistic performance and energy retention compared to 5.56mm. For personal defense, .300 Blackout also offers good terminal ballistics at typical engagement distances.

I think the ideal use case scenario for a 300 BLK build is a suppressed short-barreled rifle at the beside with subsonic rounds OR as a dedicated truck/backpack rifle due to the compact size. 


Not everything is perfect. Here are some reasons why someone should choose 5.56 NATO over .300 Blackout:

1– Longer Range and Penetration: 5.56mm NATO generally offers better long-range performance and penetration compared to .300 Blackout. The 300 BLK caliber typically is performing at 200 yards or less while 5.56 can tickle targets at almost twice that effective range (and further if you're a good shot).

2– Availability and Cost: 5.56mm NATO ammunition is much more widely available and generally less expensive than .300 Blackout. This can be an important consideration for high-volume shooters or those on a budget. 

3– Military and NATO Standard: If compatibility with military or NATO forces is important (for example, in a survival scenario or for interoperability), 5.56mm NATO is the standard and widely recognized caliber. In a SHTF scenario I would imaging you are going to come up upon much more 5.56mm ammunition out there. 

    The fact of the matter is, I don't shoot my .300 BLK rifles as much as my 5.56 ones and the ammo prices / storage of multiple calibers can be a hinderance to that. 

    P.S. if you're looking for stickers to organize your ammo cans, I got you covered.

    Closing Thoughts

    In summary, the choice between.300 Blackout and 5.56mm NATO depends on factors such as intended use for the caliber (e.g., hunting, home defense, military use), desired performance characteristics (e.g., range of engagement, terminal ballistics), and logistical considerations (e.g., cost, availability, compatibility). Each cartridge has its strengths and is suited to different applications. But there is something to be said about simplicity.

    If all of your rifles are chambered in 5.56mm NATO then you aren't missing out on much. 

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