Thinking about RECOIL

Ponyman · 01-13-2006, 05:46 PM

Kick (recoil) - from a Mechanical Engineer's point of view:

For every action, there is an equal and opposite reaction. The force that applies an impulse to the bullet and launches the bullet out the barrel exerts an equal and opposite impulse on the gun. The impulses are co-axial: the bullet travels out the barrel, and the recoil is directed in the opposite direction (toward the shooter) ALONG THE REAR-WARD EXTENSION OF THE CENTERLINE OF THE BORE. The gun is (partially) restrained from rear-ward motion by the shooters hand. The impulse perceived by the shooter (recoil) is matched by an (almost) equal and opposite-direction impulse applied by the hand to the (grip of) the gun. The bore is some distance above the grip, so the two impulses applied to the gun tend to rotate the gun. In engineering terms, two forces tending to rotate an object are said to be appling a "moment". This is the "upward" component of the recoil. If a pistol was constructed so that the barrel was an extension of (co-axial with) the shooter's forearm, there would be no rotating "moment" and no upward kick. The AR-16 uses exactly this principal - the rear-ward extension of the bore centerline passes through the stock to the shooter's shoulder. A pistol of such design would have its entire mechanism - hence most of its weight - forward of the shooter's hand, and would not balance well in the hand. (The Mauser broomhandle has such a forward action, but the barrel remains above the grip.)

Not having any other high-powered pistols to compare with my Lugers, I offer the following as conjecture to be checked by other members. (:-)

The reason for the Luger's reduced upward kick (compared to a pistol of similar weight firing a similar cartridge) is that a Luger's barrel is a smaller distance above the grip, which reduces the applied "moment". This is due to the Luger's trigger linkage being located BESIDE the barrel, whereas most other designs must elevate the barrel in order to make room for the linkage BELOW the barrel.

Comparative measurements, anyone? My suggestion would be to measure the vertical distance between the bore centerline and the forward-most point of the backstrap, where most of the recoil is transferred to the web of the shooter's hand (and the point about which the pistol tends to rotate).

unspellable · 01-16-2006, 06:38 PM

There may be some merit to your contention. I'll have to compare a Luger to some other pistol tonight.

Another factor at work here is the toggle. As the action opens the toggle and some part of the linkage mass is pushed upward tending to push the pistol downwards. In effect, it's a mechanical compensator.

It would be interesting to figure out which of the two factors has the greater effect. I've always thought the Luger had less subjective recoil than any other 9 mm of comparable weight.

And any self loader tends to spread the recoil at the grip over time compared to a single shot pistol or conventional revolver.

There are handguns in which the bore is set lower, some so low as to be more or less coaxial with the fore arm.

pipeman45 · 01-17-2006, 02:22 AM

Felt recoil is such a subjective thing. To some a Luger is soft. To others it jumps. I think it has a lot to do with how the gun is held,and the shooters experince with other pistols. The first time I touched one off in a Luger I could sure tell it wasn't a 1911. But I liked it anyway!

unspellable · 01-17-2006, 08:05 AM

Approximate measurements from center line of bore to center of trigger in inches:

DWM Parabellum: 1-1/4

Star PD 1-1/2 (The original compact 45)
Glock 20 1-1/2 (10 mm)
Ruger P89 1-1/2 (9 mm)
Start Firestar 1-3/8 (Compact 40 S&W)
Llama IX-C 1-5/8 (1911 clone)

Looks like other pistols typically have the barrel about a quarter inch higher than the Luger.

01-13-2006, 05:46 PM	#1
Ponyman User Join Date: Feb 2005 Location: Atlantic County, NJ, USA Posts: 138 Thanks: 0 Thanked 1 Time in 1 Post	Thinking about RECOIL Kick (recoil) - from a Mechanical Engineer's point of view: For every action, there is an equal and opposite reaction. The force that applies an impulse to the bullet and launches the bullet out the barrel exerts an equal and opposite impulse on the gun. The impulses are co-axial: the bullet travels out the barrel, and the recoil is directed in the opposite direction (toward the shooter) ALONG THE REAR-WARD EXTENSION OF THE CENTERLINE OF THE BORE. The gun is (partially) restrained from rear-ward motion by the shooters hand. The impulse perceived by the shooter (recoil) is matched by an (almost) equal and opposite-direction impulse applied by the hand to the (grip of) the gun. The bore is some distance above the grip, so the two impulses applied to the gun tend to rotate the gun. In engineering terms, two forces tending to rotate an object are said to be appling a "moment". This is the "upward" component of the recoil. If a pistol was constructed so that the barrel was an extension of (co-axial with) the shooter's forearm, there would be no rotating "moment" and no upward kick. The AR-16 uses exactly this principal - the rear-ward extension of the bore centerline passes through the stock to the shooter's shoulder. A pistol of such design would have its entire mechanism - hence most of its weight - forward of the shooter's hand, and would not balance well in the hand. (The Mauser broomhandle has such a forward action, but the barrel remains above the grip.) Not having any other high-powered pistols to compare with my Lugers, I offer the following as conjecture to be checked by other members. (:-) The reason for the Luger's reduced upward kick (compared to a pistol of similar weight firing a similar cartridge) is that a Luger's barrel is a smaller distance above the grip, which reduces the applied "moment". This is due to the Luger's trigger linkage being located BESIDE the barrel, whereas most other designs must elevate the barrel in order to make room for the linkage BELOW the barrel. Comparative measurements, anyone? My suggestion would be to measure the vertical distance between the bore centerline and the forward-most point of the backstrap, where most of the recoil is transferred to the web of the shooter's hand (and the point about which the pistol tends to rotate). __________________ "The Constitution is intended for use by a moral and religious people. It is wholly inadequate for the governance of any other." ~ John Quincy Adams

01-16-2006, 06:38 PM	#2
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 768 Thanks: 0 Thanked 19 Times in 11 Posts	recoil There may be some merit to your contention. I'll have to compare a Luger to some other pistol tonight. Another factor at work here is the toggle. As the action opens the toggle and some part of the linkage mass is pushed upward tending to push the pistol downwards. In effect, it's a mechanical compensator. It would be interesting to figure out which of the two factors has the greater effect. I've always thought the Luger had less subjective recoil than any other 9 mm of comparable weight. And any self loader tends to spread the recoil at the grip over time compared to a single shot pistol or conventional revolver. There are handguns in which the bore is set lower, some so low as to be more or less coaxial with the fore arm.

01-17-2006, 02:22 AM	#3
pipeman45 User Join Date: May 2004 Location: Kentucky Posts: 539 Thanks: 0 Thanked 1 Time in 1 Post	Felt recoil is such a subjective thing. To some a Luger is soft. To others it jumps. I think it has a lot to do with how the gun is held,and the shooters experince with other pistols. The first time I touched one off in a Luger I could sure tell it wasn't a 1911. But I liked it anyway! __________________ Dave

01-17-2006, 08:05 AM	#4
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 768 Thanks: 0 Thanked 19 Times in 11 Posts	Barrel height Approximate measurements from center line of bore to center of trigger in inches: DWM Parabellum: 1-1/4 Star PD 1-1/2 (The original compact 45) Glock 20 1-1/2 (10 mm) Ruger P89 1-1/2 (9 mm) Start Firestar 1-3/8 (Compact 40 S&W) Llama IX-C 1-5/8 (1911 clone) Looks like other pistols typically have the barrel about a quarter inch higher than the Luger.