by J, B. Wood | Contributing Editor
“Bump Stock!”
A complete Slide Fire stock.
The term was probably coined by some media person, ignorant of firearms and the laws of mechanical motion. The “Bump-Stock” does not “bump” anything. I’ll admit that I have never handled one, but from photos I’ve seen, its operation is obvious.
The stock is held firmly against the shoulder. A forward extension forms a rest for the trigger finger. On firing, the entire action, barrel and receiver, goes to the rear in recoil. Then, spring-powered from the stock, it goes back forward, bringing the trigger back into contact with the trigger finger.
Close up shows how stock butts against trigger finger.
The result is a simulation of full-auto firing. I suppose you could say that the trigger “bumps” the finger, but the name of the Texas firm that makes this accessory says it more accurately: “Slide-Fire.” When it was first made, a few years ago, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) did not ban or regulate it, because mechanically, the rifle was still semi-auto.
Now, of course, the anti-gun crowd is screeching for a ban, since the nutcase in Las Vegas apparently used the gadget.
Predictably, gun shops all over the country immediately sold out of the few they had on hand, and prices began to escalate.
The manufacturer’s phone has a recording that “further messages cannot be accepted at this time.”
A practical note: firing short three to five–shot bursts should cause no problems. However, the standard AR-type rifle is not designed to be a full-time machine-gun. If you were to run through two or three full magazines, the fore-grip would probably melt.
No spring involved in bump stock operation
Dear Editor:
Re: Bump stock article by J. B. Wood, TGM, Nov. 2017, page 36.
As I told you back right after Las Vegas, I was Minnesota counsel for Slide Fire on the “machine gun” question. Many mainstream media were misrepresenting the action of the bump stock as “recoil operated,” as opposed to the design requiring forward pressure on the handguard in order to make it work. If you do not maintain forward pressure on the rifle to counter the pressure of the stock being held against the shoulder, it will not cycle, because the trigger doesn’t bump the trigger finger after it resets as it fades from the finger. If one fires a round and releases the forward pressure, the action recoils into the stock and stays there.
Unfortunately, J. B. Wood doubles down on the inaccuracy with his mention of the bump stock being “spring-powered.” He is very accurate, except for the spring:
“The stock is held firmly against the shoulder. A forward extension forms a rest for the trigger finger. On firing, the entire action, barrel and receiver, goes to the rear in recoil. Then, spring-powered from the stock, it goes back forward, bringing the trigger back into contact with the trigger finger.”
He admits that he is unqualified to write about it [“I’m not a real doctor, but I play one on T.V..”]: “I’ll admit that I have never handled one, but from photos I’ve seen, its operation is obvious.”
Well, sort of. If he had looked carefully at the photos, he would have seen that there is no butt stock behind the buffer tube which would allow the placement of a spring in a chamber to operate in the fashion which he describes. THAT WAS DONE PURPOSEFULLY by Slide Fire in order to make it both difficult and obvious that the addition of a spring to their design was aftermarket and unauthorized, because the presence of a spring would have made the gun fully automatic in that the energy of the recoil would have been harnessed and redelivered to cause the stock to operate with more than a single shot with a single depression of the trigger. In fact, during my research into the Slide Fire stock, I encountered a decision of the ATF concerning a proposed stock for a Ruger 10/22 which operated with a spring capturing the recoil energy of the action and re-delivering it to the action and causing it to bounce forward into the finger after trigger reset in recoil. ATF decided that the spring made the firearm fully automatic in that a single depression of the trigger allowed the rifle to fire multiple times (until the ammunition ran out). Sound familiar? Whereas the Slide Fire required manual operation of the forearm/handguard to move the action forward and causing the trigger to bump the finger, the same as removing the finger from the trigger to allow reset and then manually applying pressure to break the trigger for another shot.
SMALL, BUT VERY IMPORTANT, CRITICAL, DETAILS, and which J. B. Wood got literally backwards. BECAUSE, “never handled one . . ..” He also didn’t read the instructions which come with the stock. But a picture is worth a thousand words, right?
Maybe not here.
Go to Slide Fire’s site (which I haven’t visited in years) and see “how it works.” Nothing about “spring” and everything about forward pressure: slidefire.com/how-it-works.
David M. Gross
Faribault, MN
