SlideFire Bump-SAW Concept

This isn’t really a forgotten weapon, but it is a very fun concept gun that my friend Karl put together while we have been experimenting with the Slidefire stocks. These are stocks that allow a rifle to “float”. The idea is that you hold your trigger finger in a fixed position and pull the rifle action forward. This causes you to fire the gun, and recoil then pushes the action backwards into the stock and resets the trigger until your continued forward pressure on the action pulls the trigger into your finger again. That may not make a lot of sense, but we have some slow motion footage of it working in the video below.

What makes these interesting is that by US law, a gun like this is not a machine gun, and may be owned by anyone who can legally own any typical rifle. With some experimentation, we found that single stage triggers with light pull weight make a big difference in allowing a Slidefire gun to run smoothly and easily. With this setup (and a 20″ heavy chrome-lined barrel), the gun comes remarkably close to the effectiveness of a true squad automatic weapon.

In fact, when we sent our friends at KE Arms some clips form this filming session, they thought it was a cool enough concept that they decided to build a rifle to this spec and offer it for sale. If you’re interested in having one yourself (complete with our logo on the receiver!), check it out:

KE Arms’ InRange Poor Man’s SAW


  1. Pretty nice shooting from a semi auto.

    You might want to look into the Recoil rail!

    I saw these a while back. Basically its a spring assisted front grip/bipod that helps put the gun back into your finger! I would love to see this compared! I have a Registered M16, so I have not gone down this path but would think its a pretty useful device!

    Also, I see where an AR with a bumpfire stock gets you to a poor mans M16 but where are you getting SAW from. If you want to claim that, you really need to drop a ARES Shrike on it. You can’t claim a poor mans SAW without a belt!

    • With 60- and 100-round magazines, I think you meet the SAW concept just fine (like the Ultimax, for example). Mags are significantly more convenient to carry and much faster to change than belts, so why not?

      • You can stick a 60 or 100 round mag into any AR-15 or M16. Does not make it a Squad Auto Weapon worthy of M249 replacement. Even with the heavy barrel you don’t really have any of the features that differentiates a M249 SAW from a M16. Otherwise the military would issue heavy barrel and Surefire/Beta 100rd mags and get rid of the LMG class.

        That said, to counter my own point you do have the Colt IAR which did seem to actually be what you are getting close too. However even in this case its consider an Automatic rifle, not a SAW or LMG.

        So I grant some LMGs use mags and some LMGs have heavy fixed barrels. However I can’t think of any off hand that have both fixed heavy barrel and are mag fed. BAR, Chauchat… but they are Auto rifles not LMGs. Damn… Lewis gun… but even there there is a non-standard way of cooling the barrel on it and certainly is the odd ball in the group of guns considered LMGs.

        I have a buddy in my MG club that has a Shrike upper on a AR15 semi lower with a bump stock. Now he has a poor mans SAW! I suggest you have a poor mans M16 or Automatic Rifle.

        I guess its really all “marketing” but to me I hear poor mans SAW I expect something modeled after a M249 and seeing an high cap mag on a HB AR15 just seems like its being over hyped. A poor man’s M16 sounds cool and when you see it, you appreciate it for what it is… IMHO.

        • “I can’t think of any off hand that have both fixed heavy barrel and are mag fed”
          Polish Browning wz. 1928

          which was used by Polish Forces during German invasion in 1939 (search for “Fall Weiss” for more information).
          In Wehrmacht service it was designed lMG 28(p) which mean “light machine gun 28 (Polish)”

          • Not mag fed in the strictest sense, but the Japanese Type 11 also had a fixed heavy barrel. And let’s not forget the French MAC 24/29, which in English is usually called a light machine gun, although a more accurate translation of fusil-mitrailleur would actually be “automatic rifle”.

            In general the difference between an “automatic rifle” and “light machine gun” was almost non-existent in the 1930s and during WW2. There was no clear consensus definitions acknowledged by everyone and national practices varied. Basically it came to what the designer or user organization of the weapon decided to call it.

          • Haha…

            My bump SAW could very easily be able to “be a worthy replacement for the M249” ….

            For whatever that’s worth any way since the M249 was nowhere near the best gun in the group of guns that were part of the competition for the SAW contract…

            So, yeah I think my gun’s got this.

            First off my bump SAW has the MGI upper and lower

            So not only do I have a quick change barrel capability as well as a 5.56 & 7.62×39 magazine well.

            When running 7.62×39 I have plenty of drum mags and two identical “custom” barrel assemblies both of which are 18″ melonite coatings a “special” fluting pattern and a sort of M231 derived heavy profile on them.

            Oh and yeah I have the gas tube fragility situation well in hand, and no I’m not telling you how…

            I also made my own bump stock being extremely careful about making sure that it would be nowhere close to an NFA violation!

            However that was a quick little just for kicks build from 2 years ago.

            What I’m working on now though… It’s got some very interesting potential!

            Oh and FG42 is another.

  2. Interesting, on the 100 round magdump, you can see the ejection pattern change as the magazine empties, it goes from 5-o-clock to more of a 2-o-clock. Would this be because of the increased friction on the bottom of the bolt carrier at the beginning abating as the magazine empties and allowing the gun to cycle a little faster at the end?

    • I don’t think the rate of fire is changing – I think the ejection pattern is changing because the gas behavior is changing slightly as the gun heats up, similar to the effect with the suppressor.

    • FWIW, I noticed a similar phenomena in Ian’s recent Broomhandle Schnellfeurer post. On that gun, the ejected cases would come out forcefully and strike behind the ejection port and rise rapidly with a full mag. As the mag emptied, they more or less burbled out of the ejection port. I interpreted this as being due to the empty brass being tensioned by not only the extractor spring, but also the magazine spring acting through the top round still in the magazine.

  3. Also, If you haven’t already, take a look at the ALG AKT trigger for your RPK. Not sure if it’ll fit the RPK but it’s got a rolling break, short reset. Might help your RPK poor-man’s SAW effort.

  4. Hook this up with a Shrike (or similar) belt fed upper and FUN TIME!!! Or mebbe rig up an RPD with one of these stocks!!! WOW!!!

  5. Another “poor man’s” idea that could be used with this concept is coupling mags. Not side by side, but bottom to bottom to combine capacities. There’s a few options on the market, but I took 2 30 round PMAGs, took off the base plates, then simply joined them by duct tape. Both springs work in unison and I was able to fit a full 60 rounds in there. I even dumped the entire mag on full auto and it worked just fine. You can search Youtube for “60 round pmag full auto” to see it.

  6. Do you have any idea as to about what the rate of fire is for this combination?

    Also, how heavy is the buffer(is that the correct name)? Have you tried different weights for this?

    Thanks for showing what you’ve found.

  7. If you put a Tac-con trigger in the gun and run it along with the Slidefire it works great. Even people using the Slidefire for the first time can empty a mag with no problems. So for about $500 extra, I have a ar15 that acts like a full auto

  8. I think if someone came up with a way to have the bipod attach to the lower receiver, instead of the upper receiver, and a handle of some type to pull both receiver pins this would be even more interesting.

    Doing this would allow one to swap out the whole upper assembly about as fast as a quick barrel change could be made. Then both the barrel and receiver could cool down.

  9. “gun like this is not a machine gun”
    I assume that this is caused by NFA 1934 which states that:
    “Machine gun means any weapon which shoots, or is designed to shoot, automatically or semiautomatically, more than one shot, without manual reloading, by a single function of the trigger”
    Hence the crank-operated Gatling guns are not machine gun, as they require “manual reloading.
    But considering above statement, what how would be considered machine gun without any trigger – shooting as fast as first cartridge is cycled, and as long as belt is not depleted. It don’t shot “more than one shot(…)by a single function of trigger”. Does anybody try to execute this conception?
    Yes firing whole belt of cartridge is not rational, but these so-called “slidefire” also is – from technical standpoint of view – as it only lower accuracy.

  10. Having used the M2, M85, M60, M240, M249 & various Soviet block firearms while in Armor and later the Infantry in the US Army, I really can’t get too excited about a fake way to make a bad rifle into a worse SAW. Sorry Ian, but this this is just a POS that needs to be forgotten. Spend your money getting the Hyde amendment overturned instead.

    • It’s just plain fun!!! Turning brass into noise…The Hyde Amendment is going nowhere in THIS political/social climate…I’d spend my money on a bump fire stock first…BTW – that sh*tstain Hyde, was from my home state of NJ – yet another reason I’m happy I left that sorry place for FL in ’86…this stock beats the HADES outta the old Hellfire trigger systems I’ve owned….and still have BTW…

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