By November 11, 2013

KPOS Generation 2 Glock 19 Short Barreled Rifle SBR Review

About a year and a half ago someone on an online forum posted pictures of an unusual contraption that turned a Glock pistol into a rifle. The KPOS carbine kit is an aluminum frame that attaches to a full- or compact-sized Glock via the accessory rail. I thought the concept was intriguing concealed carry and also as a (very) lightweight alternative for Sedagive? during rifle training classes compared to the full-sized AK she was using.

I submitted my Form 1 short barrel rifle paperwork to the ATF, waited about seven months, and then bought the KPOS.

My experience with the unit has been very mixed, and I have nothing but bad things to say about the manufacturer. However, when the kit works, it makes you forget all about the bad shit you had to go through to get there.

Here’s my review.

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Features

The second generation KPOS is made out of one big piece of aluminum. It feels great and seemed to be durable without being unreasonably heavy.

The top of the KPOS is one long rail, and there are two shorter rails along the front of the enclosure. There’s also a rail on the bottom, but that’s reserved for the combination hand-stop/ foregrip / trigger safety. You’re going to need this piece, so don’t remove it.

The folding stock folds to the right hand side. As a right-hander I think this is a bad design, as I either have to reach around the enclosure with my left hand and take the rifle off target or open the stock with my right hand, which takes my hand off of the grip. You’ll like this design if you’re a lefty, or have to shoot with your other hand.

The KPOS only ships with a rear sling attachment, if you can call it that. It’s a small metal ring that I wouldn’t even trust my house keys on. The design of the KPOS prevents you from attaching a different attachment point. I’m very worried that the ring will give way at some point, but after training with it several times this year it’s held up.

The foregrip / trigger shield design is ingenious. Pistols usually live in holsters that cover the trigger area. Once you convert your Glock to a rifle the trigger is exposed. The KPOS foregrip has a spring-loaded plastic shield that covers the trigger area. You release the shield by pushing buttons on both sides of the foregrip. This design keeps the shield from being accidentally released.

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Unfortunately the implementation of the foregrip is indicative of the KPOS experience as a whole: cool idea, but a little finicky in practice. There is a pushbutton release on the foregrip that allows you to fold it back into place. The button is extremely hard to depress. I have found that wiggling the foregrip laterally helps align the pushbutton properly so you can fold the foregrip closed. Many first time shooters struggled with what should be a simple task.

Installation

Pulling down on the front of the KPOS unhinges where the pistol attaches into the frame.

You slide a Glock pistol (unloaded) into the front of the KPOS. There is a lever that turns a bar that locks the pistol into place — sort of.

If all goes according to plan, snap the front of the KPOS shut.

Next step: slide an aluminum plate over the rear of the Glock.

For the last step, pull the extended stock flush against the rear of the KPOS and push the captive retaining pin through the KPOS.

Installation problems

I had to send my first KPOS back because of an unsolved problem with getting the pistol to install into the enclosure. I could either anchor the pistol to the front of the KPOS via the tension bar or get the rear to install correctly. I couldn’t do both — the front of the KPOS would snap loose.

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My Glock horribly out of alignment with my first KPOS. Mako never explained why this happened.

Additional, the rolled pin that held the attachment lever in place fell out repeatedly.

Mako’s support was slow and didn’t have any good suggestions. I sent them photos and eventually talked to their support person on the phone. They couldn’t help me with a real pistol, and admitted all of their fitting and testing there was done with an airsoft Glock copy.

I exchanged my unit for a replacement.

It took Mako almost two months to send me another unit. The support guy said they were “busy” with trade shows, but I’m not sure why that would take them so long. The KPOS is a stocking unit, how hard is it to send a replacement?

Malfunctions and feed problems

The Gen4 Glock 19 that lives in the KPOS is very reliable. I have fired thousands of rounds through it and I have completed many handgun training courses with it.

The first time I took the KPOS to the range it would jam every other round. My longest string of firing without malfunction was four rounds.

Most of the jams looked like this:

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I sent an email to KPOS when I got home. I nagged them a week later and they finally responded — with no help. The support manager said he’d “ask the manufacturer” and get back to me.

At this point I knew better than to wait for them to get back to me, so I went back out to the range. My friend suggested I remove the deflector shield that was screwed into the KPOS frame. I did — and taking the angled shield off helped a lot.

Almost two weeks passed and I hadn’t heard from Mako, so I wrote them again. Two days later they replied, stating that they hadn’t received any more information from their manufacturer.

I never heard from them again.

Training and confidence

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Sedagive? and the KPOS

I decided to run a few drills and classes with the KPOS. I tried various Glock and third-party magazines as well as several types of ammunition, including my Federal HST carry ammo.

Best results were with Brown Bear ammunition firing from KCI (Korean) 33-round magazines downloaded to 31 rounds with a factory Glock baseplate. Glock factory mags were actually a little less reliable than the Korean ones, if you can believe it. That’s the bizarro world of the KPOS.

Some days were better than others, but I never completed a training session without a malfunction.

I am not 100% sure why, but I have two theories on why the KPOS isn’t more reliable:

  1. The Glock 19 is too short for the enclosure. Even though the Glock will eject spent brass at a rearward angle, I don’t think it’s enough to reliably clear the ejection area of the KPOS. Shooting at different angles, such as from behind / under concealment, makes this worse. Oddly, shooting with the KPOS completely on its right (ejection port) side makes it the least reliable.
  2. Mounting the KPOS to the polymer frame of the Glock is problematic. I think part of the problem with feeding / ejection is that the KPOS is either too tightly or too loosely attached to the accessory rail. Worse yet, the tension changes over time from too tight to too loose. I think there’s a sweet spot wherein the KPOS works really well. Unfortunately I have no way of discerning this.

Over many sessions of fiddling with the KPOS, I recommend the following:

  • Fold the retaining lever pointing towards the muzzle. I don’t know why this makes a difference compared to pointing it towards you, but it seems to.
  • Make sure the Glock is absolutely centered in the KPOS unit. Putting too much or too little force on the locking lever may cause the polymer frame to twist slightly. Things have to be dead on.
  • Remove the deflector shield from the KPOS. Just two bolts and you’re good.
  • Use a Glock 17 instead of a 19.

Here’s my video review of the KPOS. Towards the end there’s some footage of me using the KPOS.

Conclusion

On paper the KPOS was great. I endured the long wait with the ATF to get my NFA stamp only to have a lot of problems with the KPOS and Mako.

It’s hard to admit when a good idea doesn’t work out so great, but I will: I regret buying the KPOS.

I’ll continue to tinker with it, but I am not sure what it will take to make it run 100%.

Not recommended — but if you have a Glock 17 and are willing to give it a try, I recommend bypassing Mako and buying it from Amazon in case something goes wrong.

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2 Comments on "KPOS Generation 2 Glock 19 Short Barreled Rifle SBR Review"

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  1. Todd says:

    Hey Doc,
    Thank you for taking the time to create and post what is currently the most comprehensive and unbiased review of the KPOS out there.

    My situation: awaiting my SBR stamp (@ 9months out, so am getting antsy,) for my Glock 21, which I hope to run with a Gen2 KPOS and a Ti-RANT suppressor. So I haven’t yet purchased the KPOS, but am researching and getting my act together once NFA goodness arrives.

    (Side note for others just getting into this: ATF now has an e-file system for SBR (Form1) applications, which according to some on forums is taking as short as 4 months to receive a .pdf stamp…making me wonder if I could have done this in December and had it sooner than my snail mail one.)

    Like you, I have not had emails or calls returned from the Mako Group, so will not make a purchase from them and will likely go with Amazon. Perhaps Mako will sell more of the new, similar, KPOS (Pathfinder, which has a buffer tube attachment rather than a stock, thus not requiring a SBR stamp) and hire some responsive folks that would be interested in helping.

    I am hoping that the longer slide of the G21 (similar to your analysis on the G17 over the G19) will make for a tighter fit in the enclosure.

    The fact that the pistol will move in the KPOS, such as when you charged the handle, concerns me. Did you find that after such wiggle, or after removing and re-inserting the pistol (successfully aligned,) into the KPOS, that your sights ever returned to zero? I also wonder if there are places on the slide or KPOS that could be shimmed or otherwise “beefed up” (tape 1st comes to mind,) to get a better overall weld?

    I am most wondering what the weight of my can on the front end might do to the KPOS’s grip on the G21. I notice that you ran 30-round mags (and am glad I also have the Korean ones!) in the unit somewhat successfully. As I consider these larger (suppressor and extended mag) attachments to the pistol, it seems likely they could aggravate movement in the enclosure.

    If you have insight to what a suppressor does to the KPOS’s reliability, I would love to hear it. If not, no worries – your taking the time to review this has motivated me to return here and post my experience with my rig once I run it!

    • DrFaulken says:

      Hi there! Thank you for writing. I’ll do my best to answer your questions:

      Q: The fact that the pistol will move in the KPOS, such as when you charged the handle, concerns me. Did you find that after such wiggle, or after removing and re-inserting the pistol (successfully aligned,) into the KPOS, that your sights ever returned to zero?

      A: The mounted optic holds zero just fine. You won’t be using your Glock’s iron sights once you’ve snuggled it inside the enclosure.

      Q: I also wonder if there are places on the slide or KPOS that could be shimmed or otherwise “beefed up” (tape 1st comes to mind,) to get a better overall weld?

      A: I wish the rail on the Glock frame had a metal reinforcement under the polymer. This is what really needs to be beefed up in my opinion. I don’t have a Glock with one of those beavertail things, but I wonder if that would help.

      Q: As I consider these larger (suppressor and extended mag) attachments to the pistol, it seems likely they could aggravate movement in the enclosure.

      A: Even a 33-rounder isn’t heavy enough to put appreciable weight on the back of the enclosure. I wouldn’t worry about the magazine. Now, about that suppressor ….

      Q: If you have insight to what a suppressor does to the KPOS’s reliability, I would love to hear it.

      A: Unfortunately I live in a state that doesn’t allow the ownership of suppressors. From handling suppressors at the SHOT Show this year I don’t think a 9mm can would be heavy enough to cause a problem, but I don’t have any experience and so I won’t say definitely one way or another.

      Have you considered the RONI from CAA? It isn’t as small, but after handling one at SHOT it’s a really nice piece of hardware.