There seems to be a misunderstanding of the similarities and the differences between these two basic designs. so I thought I might be able to clear up some of it.
First, let’s look at what recoil is and where it comes from…what causes recoil.
Recoil is the reaction side of an action-reaction event. Newton’s 3rd Law states that for every action, there must be an equal and opposite reaction. You can bring recoil into play by simply throwing a baseball, but for this discussion, we’ll just stick with guns.
We all know recoil as the backward movement of a gun when it’s fired. No mistaking it. But, what is recoil in the context of a recoil operated autoloading firearm? Simple. The recoil impetus is used to drive the breechbolt backward. In the auto pistol, we call this breechbolt the “slide” which is the heart of the auto pistol’s function.
There are pistols that operate on a simple blowback or “straight” blowback principle, and there are those that operate on the locked breech, recoil operated principle which I prefer to call unlocked breech and locked breech blowback, respectively…and the locked breech pistol is more accurately described as a Delayed Blowback, but that’s meat for another discussion. For simplicity’s sake, we’ll stick to these two basic designs.
Back to Newton’s Action and Reaction.
An action-reaction system is comprised of two interacting objects…or reactive masses…and a vectored force between them..actually two forces. A force forward and a force backward. These two forces are of equal magnitude and they occur at the same instant. Just as there cannot be an action without a reaction, there cannot be a force forward without a force backward.
So, let’s start by describing a straight blowback operation.
We have a barrel and a breechblock/slide. We have a cartridge. When the propellant in the cartridge case burns, it creates expanding gases which result in pressure which creates a force. Force forward and force backward. Force forward drives the bullet and force backward drives the slide.
And there it is. I just described recoil…and this is often where the arguments start.
“It’s NOT recoil! It’s blowback! Recoil operated is different!”
How is it different?
With a locked breech/recoil operated pistol, you have a barrel and a slide and a cartridge and you have the same series of events that occur when you pull the trigger. How does anything change just because the cartridge is fired in a locked breech pistol? Force forward still drives the bullet and force backward still drives the slide.
Let’s look at what this guy had to say about it.
About a year ago, Walter Kulek sent me an enhanced copy of the 1911 patents that were infinitely easier to read…so I sat down and actually read them for the first time…and I ran across this description.
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Patented Feb. 14, 1911.
Application filed February 17, 1910.
Inventor J.M.BrowningThis specification signed and witnessed
this 1st day of February, A. D. 1910.
JOHN M. BROWNING.
In the presence of –
A.L. Ulrich.
K. Powers.
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It is essential for the proper operation of firearms of this class that the breech-bolt and the parts connected and moving with it should be made as heavy as practicable, so that it may store a maximum amount of energy in the short time during which on firing the rearward pressure of the powder gases in the barrel acts upon the breech-bolt and initiates its recoil, and so that the
breech-bolt may continue to recoil under its momentum alone to complete the opening of the breech and the compression of the reaction-spring after the gas–pressure has ceased because relieved by the exit of the bullet from the barrel.
Application filed February 17, 1910.
Inventor J.M.BrowningThis specification signed and witnessed
this 1st day of February, A. D. 1910.
JOHN M. BROWNING.
In the presence of –
A.L. Ulrich.
K. Powers.
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It is essential for the proper operation of firearms of this class that the breech-bolt and the parts connected and moving with it should be made as heavy as practicable, so that it may store a maximum amount of energy in the short time during which on firing the rearward pressure of the powder gases in the barrel acts upon the breech-bolt and initiates its recoil, and so that the
breech-bolt may continue to recoil under its momentum alone to complete the opening of the breech and the compression of the reaction-spring after the gas–pressure has ceased because relieved by the exit of the bullet from the barrel.
And, then a little further down…in case there’s any confusion as to how the barrel moves backward…and there often is.
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On firing, the breech-slide recoils and carries the barrel rearward until the rear end of the same, swinging rearward and downward on the link and pivot-pins,
becomes unlocked from the breech-slide. Now, if we didn’t know better, we’d think that the first paragraph was describing a straight blowback operation, and it actually could be correctly used to do that…except it’s describing the 1911 and the 1911 is a locked breech pistol.
becomes unlocked from the breech-slide. Now, if we didn’t know better, we’d think that the first paragraph was describing a straight blowback operation, and it actually could be correctly used to do that…except it’s describing the 1911 and the 1911 is a locked breech pistol.
So, unless someone wants to go on record stating that John Browning was an idiot who didn’t understand his own creation, we’re left with one conclusion.
At the end of the day…whether we’re talking about locked breech or unlocked breech/blowback…it’s an action and a reaction from force forward and force backward. They’re BOTH recoil operated and they’re both blown back. The only difference..the ONLY difference…is in the method used to delay the breech opening until the bullet has exited and pressures drop to safe levels.
Cheers!
Thank you for the best explanation of blowback and recoil operated pistols. I average 5 gun magazines a month, was a certified NRA counselor (over the hill age wise now, let the young take over) for many years and have looked up the difference between these two often.
Thanks and best regards,
Jack
If this is true, then please explain why recoil operated firearm have to be modified to fire blanks and blow back ones can fire them as is.
The pistol expert Peter Dallhammer explains it as follows:
Think of a bullet that get stuck in the cartridges mouth. This bullet is not able to move at all. The Latin definition for recoil is “sive corporum duorum actiones in se mutuo semper esse aequales et in partes dirigi” the fomular is ” mass x speed = mass’ x speed’ ” if it comes to a gun this is “bullet-mass x bullet-speed = silde(or bolt)-mass x slide(or bolt)-speed”. As easy as this. But if we stop the bullet and reduce its speed to 0 its “bullet-mass x 0 = silde(or bolt)-mass x slide(or bolt)-speed”. Multiplying any number by zero equals zero, therefore its “0 = silde(or bolt)-mass x slide(or bolt)-speed” if we then observe any movement of the bolt we have “0 = (≥1)” ore more simply “0 = 1” and anyone what payed attention in math class knows, this is wrong.
Any firearm that have a moving bolt despite a non moving projectile can not be “recoil operated” as can me proven my mathematics and physics, we call these fire arms blow back.
I was just notified of this, so forgive the delay.
I hardly know where to start, so I’ll start with this.
Action and reaction occur whenever the gun is fired, regardless of whether it’s blowback/unlocked breech, locked breech/recoil operated…or a flintlock musket. In an autopistol, recoil…reaction…is what causes the slide to move. The slide doesn’t know if it drags the barrel with it or not…whether it’s temporarily locked to the barrel or it it moves independently of the barrel.
No. An unlocked breech/blowback firearm will not work ‘just fine” with blanks without modification. It requires a barrel restriction or a blank firing adapter and reduced power spring(s) in order to function.
With all standard springs, I can get an unmodified 5-inch 1911 slide to move to the quarter cock cock notch on a Series 80 Colt with a pseudo blank made up of 5 grains of Bullseye and a tuft of cotton in the case to keep the power from spilling during loading. That doesn’t even make for a good blank, producing only a weak “pop” when fired. A full pressure blank would move it farther. Unfortunately, nobody that I know of makes real .45 Auto blanks for commercial sale. I can’t even find blank shotgun shells any more.
Think about it. If you can find any surplus .30-06 or 7.62 NATO blanks…fire them in an unmodified bolt action rifle, and there will be no recoil…or at least not enough for you to notice.
In a normal action-reaction system, you have two interacting objects and two forces…a force forward and a force backward. In a pistol, force forward accelerates the bullet and force backward accelerates the slide. Force backward produces recoil. There is no other way for the slide to move. The “straight blowback” pistol is recoil operated. That is the reality.