One of the most difficult things retailers do is try to “read the tea leaves” when it comes to the next hot cartridge.

Every few years there is an improvement on an existing mainstream round, and most are just minor adjustments geared toward very small markets. Often termed “wildcat” cartridges, they typically appeal to the reloader, hunter or target shooter and comprise little inventory. Investing as little as possible keeping customers happy without breaking the bank is the best course.   

It’s when they become mainstream that things get interesting. Investing heavily can be costly if it turns into a fad. Ignoring it can drive customers to other stores and cost sales.  

Some good examples include the 6.8 SPC for rifles and .357 Sig for pistols. Early hype sold lots of both, followed by near obscurity. The .357 Sig is slowly but surely disappearing, and the 6.8 SPC has experienced a resurgence — much like the 10mm pistol round. 

So what’s the difference? All started as military or law enforcement cartridges. All improved on existing parent cartridges.   

It can all be summed up in one word: versatility. The ability to reach a broad market meeting numerous needs.  

Tactical Sells, At Least For A While

There is little doubt anything “tactical” sells, at least for a while — with the AR being the poster child for this phenomenon. 

As a patrol sergeant looking for rifles in the 90s, I had two choices. Most retailers had no idea what they were, let alone stocked them. Hunters shook their heads wondering why you would own one.

The much-talked-about ban of the AR, followed by appearances in movies, television and video games and the eventual expiration of the ban, served to increase their popularity, and sales soared.   

Removing the initial ban slowed sales, but the “tactical” tag stuck. Entire markets grew around the platform existing to this day. More attempts at restrictions drove sales again, then the engine lost steam. 

Compared to the craziness during ban paranoia, sales are slow, but they still exist. So what’s keeping them going? Hunters, and the well-orchestrated media and industry campaign turning them into the “modern sporting rifle.” 

Focus is moving from “operator” mode to competitor or hunter mode. With 3-gun and similar competitions on the rise and guns built to meet hunting needs, sales are remaining steady without the impetus of gun bans. It’s all about versatility, and the latest “new” cartridge might be the best example yet.

Enter the 300 BLK (Blackout).

So, What Is The 300 BLK?

Many mistakenly compare this round to the 6.8 SPC, but the only similarity is their development within the U.S. military and the M4 as the original platform. 

Wanting a longer-range cartridge using the M4 rifle, the 6.8 SPC was intended to be a legitimate 500-yard cartridge. Designed around the 16-inch barrel, it outperformed the 5.56mm NATO in every category.

Along with typical logistical and political issues, its primary downfall was the need to change the bolt and inability to use millions of magazines already in inventory. 

While the 300 BLK can perform similarly in many conditions, its original design was exactly the opposite.

The 300 BLK cartridge has its more common roots as a rather obscure wildcat cartridge, the 300 Whisper. But as a wildcat round, it suffered the fate of similar rounds that weren’t put into the mass market. Manufacturers who initially locked into contracts still make it, but those contracts are ending, relegating it to relative obscurity.    

It took Advanced Armament Corporation to change this, along with a request from the military. Altering the design making it a mainstream cartridge void of royalty payments, the new 300 BLK has its beginnings in the Special Missions Units of our military. Its primary purpose was to replace the 9mm HK MP5SD (suppressed) sub-machine gun. 

The few MP5SDs in military inventory are decades old and are being removed from service. It has served well and fits several mission requirements — especially those where range is limited and silence critical. 

A replacement was required, so why not use the M4, which is standard throughout the services? Using a 6-to 9-inch barrel on standard M4 receivers, bolts and magazines using the 300 BLK meant a simple barrel change. 

Built to be fired with a suppressor, it is essentially a sub-gun using a modified rifle cartridge on an actual M4. Properly tuned, it performs this job incredibly well — much better than the weapon it replaced. Bullets in the 200- to 240-grain range fired at about 1050 fps are very effective close-range weapons. These guns work well suppressed with short barrels, exponentially better than similar 5.56mm weapons. 

If that’s all they did, the story would end there. Much like the 6.8 SPC, look outside the original intent and it becomes a versatile cartridge reaching a broad range of users, far more than the 5.56mm NATO and even the 6.8 SPC.

300 BLK — Not Just For Ninjas!

For those able to afford and legally own a suppressed short-barreled rifle capable of shooting subsonic ammunition, they are a ton of fun. It is a fantastic platform to sell suppressors. While incredibly quiet, the recoil rivals a .22 long rifle. Limited to subsonic rounds, most 9mm pistol suppressors will even work.  

Just be careful, as the rifle will shoot supersonic loads, and many 9mm suppressors will not. It is a solid sales opportunity for customers already in possession of sub-gun suppressors knowing the limitations. Or, it’s a chance to carry new suppressors like the Liberty Mystic X that will handle full-power loads.    

Ammunition companies are starting to make subsonic ammunition designed to expand. Still, as a practical matter, most overpenetrate and underexpand, making it mostly fun time at the range. It does this well for sure, but it’s not the sweet spot to generate sales. Moving to rifle suppressors and full-power ammunition gets you the best from this platform.

Most 300 BLK ARs tuned to run subsonics reliably will not run supersonic ammunition well — despite the marketing. Having tested several, I can tell you it is generally an either/or proposition. Even so, adjusting between the two is pretty simple. Most of the time a simple swap of buffers or springs will do it. 

For complete versatility, adjustable gas blocks are the ticket. Take that same tactical “ninja” rifle, turn down the gas, swap in an H2 (or similar)buffer, add a rifle suppressor and purpose-built self defense ammunition, and you have what might be the perfect home defense AR. 

Unlike most 5.56 NATO guns, the 300 BLK suppresses reliably, operating with very short barrels using simple and inexpensive direct impingement systems. Using a 9-inch barrel, my Seekins Precision SBR is dead nuts reliable with almost precision accuracy. Loaded with 110- to 125-grain expanding bullets, it provides optimum wound ballistics. 

Barnes Tac-X bullets are common, although 125-grain Nosler and similar are impressive in gelatin. Using Remington’s 125-grain match, it shoots at 1/2-MOA with consistency out to 300 yards. Even with a 9-inch barrel, it holds its own against the 6.8 SPC using shorter barrels out to 300 yards. It delivers similar energy at the muzzle as a 14.5-inch M4 in 5.56mm.

Adding several .30-caliber rifle suppressors, it remains very quiet even in close quarters. Recoil is all but nonexistent. Add something like a Law Tactical Gen3 folding mechanism and you get a compact powerhouse. To me, this is the clear sweet spot for the cartridge and provides the most versatility.   

Hunting With The 300 BLK

Generally, failing to make the jump to hunting signals the death knell for most specialty military cartridges. Making that transition kept the 6.8 SPC afloat, driving most of its market today. In the last year or so, the 300 BLK is making that transition nicely, providing an entirely different market for retailers.  

Given the range of .308 hunting bullets that will work, loads designed for hunting deer, hogs, coyotes and other small- to midsized game are becoming widely available.  

Think of it as a .30-30 out of an AR — soft-shooting, accurate, with solid energy on target, it is a great hunting cartridge.

Turning your existing .223 AR into a 300 BLK requires a simple barrel change. Utilizing a .223 bolt and AR magazines makes the transition easy and inexpensive. Stocking barrels, even with freshly fitted bolts, is a moneymaker.

And being able to swap them out is also a solid sales opportunity. Given little ballistic advantage to longer barrels, 16- to 16.5-inch barrels keep the rifle handy for hunting. Sending most factory 110-grain bullets downrange at 2400 fps or so, they can be very accurate.  Moving to 125-grain bullets, velocities hover in the 2,100 to 2,200 fps range — impressive for a small AR rifle. 

And its ability to work in any .223-based action only increases its versatility. 

Today, just about every mainstream manufacturer offers a bolt rifle in this caliber. Without AR reliability issues, moving from subsonics to supersonic ammunition is seamless. Our extensive testing using a Remington SPS Tactical dropped in several stocks yielded some impressive results. Many avid hunters are moving to the 300 BLK for hunting inside 300 yards. Recent advances in expansion using subsonic loads seem promising, adding another other variant to the hunting capabilities.

Rifle-Caliber Pistols

One of the latest crazes is the rifle-caliber pistol.

While recent ATF decisions concerning the SB-15 Pistol Stabilizing Brace use may impact sales a bit, rifle-caliber pistols remain the hot ticket this year. Most are chambered in .223 — neither the most effective nor reliable round when barrels get this short .

Given its initial design to be used with a pistol-length gas block, the 300 BLK is perfect for this weapon. Ballistics are far superior to the 5.56mm, reliability is better and they suppress easily, offering a usable pistol with viable terminal ballistics. 

Reloading The 300 BLK

If you already load .223 or 5.56mm ammunition, making the transition to 300 BLK is downright simple. 

Using 300 BLK brass, it is just a set of dies. Converting .223 brass requires some trimming. Beyond that it is pretty much the same. 

Using less powder than the .223 in most cases is generally cost effective. As things settle down from last year’s frenzy, it’s getting less costly quickly. Utilizing .308 bullets, the 300 BLK accepts proven hunting versions from 110 to 125 grains. Practice ammunition is often loaded with 147-grain bullets, while subsonic loads go as large as 240 grains.  

Fitting in standard AR magazines, it is very generous when it comes to overall length. Generally, if they fit in the magazine, they load, and short bullets seem to work just as well.  It allows you to load everything from cost-effective practice ammunition for range use to higher velocity hunting and target rounds exhibiting excellent accuracy.

300 BLK Is Here To Stay

No rifle round is the “perfect” or “best” anything.  They all serve a purpose with varying strengths and weaknesses. 

Replacements for the 5.56mm NATO and .223 have come and gone with regularity over the years. Most provided advantages with noticeable or costly shortcomings.  With problems ranging from proprietary magazines and ammunition, to reliability and accuracy issues, they all either failed or experienced marginal success. 

Retailing them was problematic at best, serving niche markets with low or nonexistent profit margins. 

It is looking like the 300 BLK might be the exception to the rule, suffering few of those issues. Barrels are priced the same as many 5.56 equivalents utilizing the same bolt and current AR magazine. Reliability exceeds the 5.56mm in every barrel length, especially pistol lengths. No piston system is required for suppressor use; in fact they work better using DI systems. The 300 BLK is viable for use ranging from self-defense pistols to hunting bolt rifles, and it has the broadest market of any recent offering. 

Its only downside to this point is popularity, driving up component costs — but even that is subsiding.

Given proper thought and preparation and some time for costs to come down, the 300 BLK is going to be a real money maker at the retail level — so take the time to understand its strengths and broad appeal. It may just do wonders for the bottom line.