Compact ARs are fun and practical if storage space is an issue, such as if you’re using one as a truck gun. Even if you have a short barrel rifle (SBR), or an AR pistol for that matter, one of the limiting factors has always been the buffer tube sticking out the rear of the gun. While there are some folding stock options out there, there are drawbacks including that some can’t be fired with the stock closed, and others add considerable cost to your build. Some require custom bolt carriers as well.
A shorter buffer tube helps in that area, although the couple of models that have been out until now have again cost a lot more than a standard carbine buffer assembly. Enter KAK Industry and their Mini Milspec Buffer Tube.
KAK Industry has been offering quality, US-made AR parts since 2011 at very competitive prices. They’ve also come up with some pretty innovative offerings especially in terms of muzzle devices and buffer tubes.
When I was building my N-23 inspired SBR I needed a short buffer assembly and the only options out there were the $500 LMT PDW stock assembly, or the LWRC UCIW set which was $140 bucks. I went with the LWRC set, although I didn’t even really need the stock itself since I was going to use a chopped CAR stock for my project.
Meanwhile, KAK Industry had put out a slick short pistol buffer tube last year that uses a flat coil spring and shorter buffer that I thought would be perfect if they did it in a carbine version. I reached out to them suggesting that, and it turns out they were way ahead of me.
Not long after that, KAK dropped the carbine version for the very reasonable price of $69.95, complete with a chopped M4 stock. If you plan on using a different stock you can get the kit without the stock for $10 less, which is what I ended up doing. KAK makes a version for rifle calibers and pistol calibers, with the main difference being the buffer and buffer weight itself. Heavier buffers are options depending on the build you’re doing for a small up-charge over the base price.
The Mini Milspec Buffer Assembly
The Mini Milspec buffer tube is just what it sounds like…a shorter Milspec buffer tube designed to reduce the overall length of your carbine or SBR. A standard carbine tube is 7 1/8 inches long and the Mini is 5 5/8 inches. KAK manages to shave inches by using a flat spring and shorter buffer assembly. The nice thing about this set up is that it uses standard bolt carriers, so you don’t any expensive, or proprietary BCG parts. It’s a swap with your existing buffer tube, or a part for a new build.
The kit comes with the five-position Mini Milspec buffer tube which is black hard coat anodized 7075 impact extrusion aluminum, a flatwire buffer spring, KAK’s mini buffer in whatever weight you select, a mil-spec end plate, and a mil-spec castle nut. You also get an M4 stock that has been cut down to take advantage of the short tube.
KAK says the flat spring increases reliability and service life and that, in conjunction with their buffer, will run like a regular carbine size assembly. You can use any standard end plate or castle nut too if you already have parts on hand that you prefer over basic mil-spec ones.
The the Mini Milspec installed you shave off about an inch and half of overall length using either the cut down M4 stock, a Magpul SL-M, or a LWRCI UCIW. The Magpul is about half an inch longer than the other two options. You can also either chop your own M4 of CAR stock as well if you decide to get just the tube assembly.
Hands On
Since I used my won stock on my N-23 build I had the LWRCI UCIW stock left over. It’s a nice stock, just more modern than I wanted for my build, but I hated seeing it go to waste. When KAK dropped their Mini Milspec tube I decided to grab one to make use of my stock. I decided to put it on my Spike’s Tactical 9mm SBR so I ordered the PCC version of the Mini with the H2 weight buffer. I was all in at $69.95, about half of what I paid for the LWRCI set up, albeit that was with the stock.
Swapping out my existing carbine buffer assembly with the KAK Mini was the same as doing any other buffer tube swap. Being that you don’t need any special bolt inserts or anything else, just take off the old tube, screw the new one on, pop the spring and buffer in, and slap the upper back in place.
The only thing you may notice that’s different is the increased tension on the flatware buffer spring. It can make it a little trickier installing the buffer, but KAK actually has a slick widget that helps you out in that department. You’ll notice a little orange L-shaped hunk of plastic in your kit.
That’s the Flatwire Buffer Spring Install Tool and it holds the buffer retaining pin down and out of the way when you install the spring and buffer. Can you do it without the tool? Sure, but it does make things easy. They even have a video showing how it works. It’s a nice add-on to the kit and I dropped the tool into my build kit box for use on other projects as well.
Your length of pull (LOP) is slightly shorter with the Mini versus a carbine tube, but nothing I found to be uncomfortable. With a jacket or plate carrier on I prefer the shorter LOP and never extended my carbine stocks all the way anyway. The LWRCI stock fit perfectly on the KAK tube so there was no issue there either. I also tried it with my cut-down CAR stock and that worked fine as well.
Knocking an inch and half off of your overall length may not sound like much, but every bit counts when you’re trying to keep things compact. It’s nice that you’re trimming that length off the rear of the gun too, and don’t necessarily have to sacrifice barrel length to save some space if you don’t want to.
As for function, well my Spike’s worked fine before I did the buffer swap, and it still works fine now with the KAK. I can’t say at this point that it increased reliability, but it didn’t do anything negative either, so that works fine for me. If KAK is correct and the flat spring enhances reliability long term that’s all bonus at this point.
If you’re looking for an easy, affordable way to shave some inches off your PDW build, the KAK Industry Mini Milspec Buffer is definitely worth checking out. It’s solidly built, works well, and is a simple to install.
Mini Milspec AR15 Buffer Tube Specs:
The Mini Milspec Buffer System is compatible with 5.56/.223 and 300 BLK, 7.62×39, and similar rifle calibers. The weight of these mini buffers and spring rate of the buffer spring mirror the functionality of a traditional carbine buffer weight/H buffer weight. Unlike most short buffer tube setups, ours is designed to function with any compatible Milspec bolt carrier group.
Compatible with 5.56/223, 7.62×39, 300 Blackout, and Similar
Proprietary Mini 5 Position Buffer Tube extends only 5.25″ from the rear of the receiver. Buffer will accept Milspec parts and stocks.
MiniMilspec Buffer Tube- Hard coat anodized 7075 Impact Extrusion
Flatwire buffer spring for increased reliability and longer life
Proprietary mini buffer weighs only 2.5oz- Carbine/ 3.3oz- Heavy and performs like a standard carbine buffer in combination with our flatwire buffer spring
Mil-spec end plate
Mil-spec castle nut
KAK Mini M4 Stock
Made in USA
MSRP: $69.95 ($79.95 with Heavy Buffer)
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