Short Action Black Magic

Am I the only one who was surprised by the rapid and exhaustive penetration of the 300 Blackout into the shooting world? I mean, I’d like to think that I had a grasp on what the hip kids shot. At first glance it didn’t even seem worthy of a second look. Sure, if your an AR guy and wanna spend a lot of time and money going movie quiet, then great, this slug’s for you. But what did it do for a guy with a serious precision rifle infatuation? Time would soon tell…
The guy that built my first custom rifle back around the turn of the century, was the first to mention it to me. He called it a Whisper, which is basically the same thing. I disregarded it as gun room talk, you know, two guys pretending to know a lot by saying things the other guy hopefully doesn’t know about?

Years later, as the blackout continued to gain market share, I found myself asking why people were building 300blk bolt guns. I had long since tailored my own sub sonic 308win loads, and to my simple mind, it didn’t make sense. A 30 caliber bullet going 1000FPS doesn’t care who pushed it there. And since the .308 had the added benefit of shooting bullets almost three times that velocity, it seemed silly to leave money on the table with the little blackout. Unless of course you were running an AR15 platform.

Fast forward to the era of my Desert Tech SRS, a rifle that most of you know dominates my trigger time. The compact and accurate SRS fit my needs like no other rifle can, and its ability to swap barrels has literally left thousands of gun collections collecting nothing but dust. I can run an abundance of calibers, both factory and custom, almost anything a guy can dream up from short action to long.

One of the last barriers in this overabundance of options for the SRS, was broken by Short Action Customs LLC a few years ago. Mark began a project that would eventually become a complete 223 conversion kit for the SRS. And before he could even sell the first one, the black plague was inquiring if he would also make a 300blk conversion kit as well.
Perhaps it was my skepticism of the blackout, that influenced his decision, or perhaps my mediocre street cred’s. But whatever the reason, Mark sent me a 300blk conversion kit to test out. A 16 inch 300blk barrel that would mate right up to the .223 bolt I already had, and a billet aluminum magazine with some slightly different cuts to it.
Testing loads
I am a sucker for load development, it’s like an attention deficit disorder. Regardless of what I’m doing, if there are empty cases on my bench, my mind wanders, considering what powder’s, what bullet’s, and the circumstances of their arranged marriage. I wasted no time getting deep into the black magic of loading this mysterious little cartridge.

Any writing about the 300blk would be incomplete without discussing its true purpose. As hinted by its name, the blackout is built around stealth. When loaded with heavy for caliber bullets, at sub sonic speeds, its sound signature is comparable to a pellet gun. The bullet is launched just below the speed of sound (a speed that varies depending on atmospheric characteristics) which in my neck of the dark woods is around 1000 fps. The slow speed of the bullet allows it to travel through the air without breaking the sound barrier, and the accompanying loud crack that some of us are familiar with. When a suppressor is added to the rifle, the report caused by rapidly escaping gasses, is also withdrawn. All that is left, is the sound of that gas escaping from the muzzle, resulting in a nearly unnoticed hiss.

In order to realize this secretive squall, quick burning pistol powders in small amounts are used. I had chosen the Hornady 195 BTHP, for many reasons but the most important one was that I was showing a large surplus in nothing else. After trying a few different loads, I found one that worked quite well. Using a mere 5 grains of Hi Skor 700X, the 195’s were hushing along just shy of the speed of sound. 700X may not be the ideal powder for the blackout I know, but when you have fifteen pounds of it, you have to find a way to make it useful. The small case of the blackout yielded more consistent velocities than .308win based sub sonic loads.

In no time at all, I found myself chuckling at the range. The incredibly quiet blackout was refreshing, and to my surprise it was pretty easy to get it to shoot well. I found myself calling cease fires, just so everybody could not hear the shot, followed by the distant metallic ping. Even my sub sonic loads had SD numbers in the low teens. With practically no load development, I was shooting near sub MOA 5 shot groups. And the supersonic loads (150gr Hornady BTSP’s) shot at almost 2000fps were even better (all accuracy testing was done at 100yds). The recoil, or lack of it was extremely satisfying, I could many times see my own bullets flying in the air on their way to the target. Like every other Short Action Customs, LLC barrel that I own, this one shoots with meticulous repetition. The accuracy, recoil, and cheap plinking fun that I have had with this little kit has certainly changed my perspective on the blackout.
100 yard 5 shot sub sonic groups, the top impact on both groups was 1st shot

With a covert ability to engage targets with the utmost concealment, this conversion kit would be perfectly suited for removing varmints from the barnyard. I suppose that LE and Military could use it for the same thing if they needed to quietly escalate something. At the same time, when loaded supersonic with lighter bullets, the blackout would also make a good short range plinking/hunting cartridge for game such as deer or hogs.

The 300blk conversion kit is a completely turn-key system, like any other conversion kit for the SRS. You simply drop the barrel in, torque it down, and swap either the bolt or bolt head depending on the configuration you have. The 10 round magazine fits right into the magwell like any other DT magazine. My kit came threaded for a suppressor, I assume they all will be unless ordered otherwise. But shooting this conversion kit un-suppressed would be silly in my opinion, as its entire enterprise is based on silence. I did experience a significant cold bore shift, whether this is a blackout thing, or a sub sonic thing, I dont know. But it is something to keep in mind for sure, when those hits have to count.
I used both a 308 suppressor, and a 338 suppressor on the little blackout, I didn’t notice any significant difference between them. But since the SRS is prone to multiple calibers, if I had to pick, I’d go with the 338. I wonder if a shorter barrel, would help lower SD numbers even further. A 10 inch blackout seems like it would be perfect, if it didn’t put my Covert on some NFA black list.

For those of you who are familiar with the 300blackout, you probably have experienced the same silly grin when you hear bullets thumping targets, as birds chirp nearby. For those of you who haven’t yet fallen under the spell, it shouldn’t take much.

I wont speculate as to when the complete blackout conversion kits will be available to order, but I believe the good people at Short Action Customs are working hard to get them ready. If you are interested a blackout conversion kit, shoot Mark an email at: mark@shortactioncustoms.com
(Dont call him and waste time because there are a lot of fine rifles being cranked out of that shop every day, and I dont need you slowing him down 😀 ) Visit http://shortactioncustoms.com/ for more information. photo credit: Ben Hetland
-CBM

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s