“Bump Fire” for Home Defense?

This is a guest post by Andrew BettsBFS-stock-3

A few years ago, a company called Slide Fire introduced a stock that allows the user to easily simulate full auto fire with a legal, semi-automatic rifle. Shortly after the introduction of that product, another company produced a copy at a lower cost and then was promptly sued. It is also no great feat to make a similar version for yourself at home and there are a number of guides available on the Internet that show you how.

Do these have any place in home defense?

Let us begin by taking a look at how the bump fire stocks work:

The user grasps the pistol grip with his or her trigger finger resting on a protrusion next to the trigger. The shooter then applies forward pressure on the hand guard with the off hand, which pulls the trigger forward against the trigger finger. The rifle fires and is able to move freely backward inside the stock, resetting the trigger. The shooter’s constant forward pressure eventually overcomes the inertia of the rifle and brings it back forward to repeat the cycle.

Because the trigger is actuated separately for each pull, and because there is no spring or other device within the stock that makes the rifle return to position, the BATFE does not consider this to be a machine gun or machine gun part.

The video above shows a fairly petite female firing an AR-15 rifle equipped with a bump fire stock for her very first time. You can see that she immediately grasps the concept and is able to control the rifle well enough to keep 3-6 round bursts on a target at home defense distances, without much effort. Bear in mind that the shooter is not really trying to do more than keep rounds on the berm.

With just a little practice, it is trivial to crank off short bursts. If single shots are desired, the shooter simply pulls the rifle back towards the shoulder and moves the trigger finger to a more traditional hold. The stock can also be easily locked in position so that it cannot bump fire.

It is possible to induce a malfunction with the wrong technique, though. If too much forward pressure is applied, the rifle moves forward too quickly and the trigger is pulled again before the bolt is fully locked. ARs and AKs have a safety feature which prevents the hammer from contacting the firing pin until the bolt carrier is fully forward so when this occurs, a live round is left in the chamber, with the hammer down. Clearing the stoppage is as simple as cycling the charging handle. Avoiding this type of stoppage is no more complicated than training people not to short stroke their pump shotgun.

From a practical standpoint, these stocks are nearly as good as real full auto in terms of being able to put rounds into a target, but SHOULD you use a device like this for home defense? Inevitably, someone will argue that using something scary or unusual will automatically put you in jail, but that really is not how use of force laws are written.

It is true that this sort of thing COULD influence a jury, but to get to that point, you would have to have been charged and indicted and for that to happen, you need to actually violate the law (offer not valid in CA, MA, HI, NJ, & NY). If you act in a safe and legal manner and only use deadly physical force when you, a reasonable person, determine it is truly necessary, then in most cases, you are not likely to go to a criminal trial. Nevertheless, the use of a device such as this presents some very real problems. As controllable as it is, it is far more likely for you to miss with a round or two from a burst. You are accountable for every single round that you fire. If one of your rounds causes harm to another person, or property damage, it will not matter how justified you were in firing it.

There is no arguing that these stocks are a LOT of fun. Not everything has to have a practical purpose. Remember, guns are fun to shoot and these things are RIDICULOUSLY fun to shoot. They might even, by a long stretch of the imagination, have a practical use for suppressive fire in a Mad Max, end-of-the-world-as-we-know-it nightmare.

They are not a particularly good choice for home defense. Any practical benefit they offer in being able to put more speed holes in the bad guy is outweighed by the risk of malfunction and increased liability.

Andrew Betts served with the Arizona National Guard for over 12 years, including a tour to Afghanistan. Visit his YouTube Channel for more great shooting information.

Photo Credit – Bump Fire Systems


  1. I bought the Bump Fire attachment from Slide fire and put it on an AK47. I am really satisfied with this arrangement. It cost a pretty penny but you get what you pay for. later I bought 2 of the fake ones. I put one on an AR15. It is cheap and hard to sustain a rapid feel in firing. For 100 dollars apiece, I threw that money away. Buy slide fire. recommended by one who knows. And I would rather use a shotgun, or pistol for home defense. You won’t need 30 rounds in a home invasion. And rifle bullets are more desrtuctive to things other than the criminal that is trying to kill you.

  2. Pierre Ferron says:

    The purpose of submachineguns is mainly for suppressive fire. This is a situation that is not encountered in a normal environment. Perhaps the ban on possession of this type of weapon was based on this premise. Therefore one could argue that automatic-fire weapons, regardless of actuation type are illegal.
    I’m not a lawyer, but does is this line of thought a valid argument?

    • No, sir. Machine guns are used for suppressing fire on the battlefield, of course. They are used to fix the enemy’s position so your maneuver element can close with and destroy them. Machine guns are also used to great effect for increasing hit probability at significant range. I had no trouble engaging targets that I could not see at 1,100 meters with an M240B because of a good assistant gunner. This is possible because of the tripod and T&E mechanism. Assault rifles and sub machine guns do not have this benefit. Sub machine guns are not particularly useful for suppressing fire and are not designed for that purpose. A sub machine gun is a pistol caliber gun with a stock and they are used to get multiple hits on bad guys at close range or to increase hit probability at ranges that would be challenging for a pistol ~100m or so. They were often issued to troops who otherwise would have carried a pistol. An assault rifle is a lightweight rifle that is chambered in an intermediate caliber (e.g. 5.56mm, 7.62x39mm, etc.) and is select fire. They are typically fired in semi but may be used in burst or auto to suppress an area as above or to get multiple hits on a bad guy at very close range. This is the application discussed in the article. Of course, the conclusion is that one should not use full auto or simulated full auto for home defense, but the tactical application is sound.

      It is not legally full auto because the rifle is still fired once by “a single function of the trigger”.

      26 U.S. Code § 5845

      “The term “machinegun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.”

    • No, since the BATFE has already approved it.

    • Where did you get the idea that SMGs automatic function is mainly for suppressive fire?

  3. The designer of Slidefire took a beating when the ATF backtracked on the legality of the device. Sold the company and then ATF reversed AGAIN, so he made the Bumpfire, and got sued by Slidefire! I have a Bumpfire on my AR15 and it functions like a dream…also my friend has one on a Colt 9mm carbine and it works flawlessly.

  4. 3hundo blackout says:

    just here to confirm what others have said, I have a $89 “knock-off” bumpfire solutions & it works flawlessly on my 9mm, 5.56, and .300blk, ar’s. although ime, it works effortlessly with a quality mil-spec trigger rather than a high end high speed or match trigger, where I’ve seen some folks may need a small learning curve when using the latter.

Leave a Reply