question for a gun scientist.

I watched this video frame by frame and the slide does move before the bullet exits the barrel...might depend on the length of barrel though

[youtube]ySO0EWIlOKc[/youtube]
 
In a locked breach pistol the slide and barrel move rearwards together for a bit before unlocking. The bullet is out of the barrel before it unlocks.
 
It definitely moves before the bullet leaves the barrel. "SHE" cannot shoot her plastic-fantastic 9mm; it throws the point of impact to the left, indicating that the pistol is moving left before the bullet leaves it. If she locks wrists it shoots just fine for her - but she can only shoot ~7 shots like that before her wrists are done for the session... :(
 
I am a gun scientist certified by the GSA group (Gun Scientists of America)

Depending on velocity and recoil, the projectile may or may not exit the barrel before the slide starts to recoil.

This in the industry is known as the Kaufmann Effect

It results in a slight loss of muzzle velocity in the 5% range if the slide starts to move before the bullet exits the barrel.

Hope this helps
 
I bet Newton would say they both start moving at the sametime. The slide would move slower because of its weight and the recoil spring resistance. The inertia might have to take longer to overcome the spring resistance?
 
If the case is not stretching, the barrel and slide are locked together and they are an enclosed system. Like a bomb building pressure, only the gases have an area to expand into as the bullet travels up the barrel. An obstacle in the barrel can change the firearms into a bomb.

Practical recoil is only felt after the projectile leaves the barrel.

I wonder how much friction the bullet exerts on the barrel and does it pull the barrel forward as it moves up the barrel.

The 2015 Gun Digest has an interesting article on recoil. For the same bullet at the same velocity, the more powder used the greater the recoil. The burning powder acts much like a rocket motor on the barrel.

However, if you are using a muzzle brake, the more powder used, the greater effect of the muzzle brake.

I would like to hear how the Kaufmann Effect is applied in these circumstances.
 
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sail32 said:
Recoil only starts when the projectile leaves the barrel.
Click to expand...

This would be a pretty glaring violation of Newton's third law of motion. And it would leave the common observation that heavy recoiling loads tend to hit higher than lower recoil loads without explanation.

Recoil starts when the bullet starts moving in the case.
 
Your right Battlerifle, I got immersed in looking up the "Kaufmann Effect", and got distracted. The post was edited.

"Practical recoil is only felt after the projectile leaves the barrel.

I wonder how much friction the bullet exerts on the barrel and does it pull the barrel forward as it moves up the barrel."
 
Depends on the pistols. If you take a Browning Hi-Power for example, the slide and barrel are locked together and will move 3/16" to the back after firing before the barrel unlocks and tilts out of the locking lugs in the slide. The bullet exits the barrel before the barrel unlocks. The barrel and slide do move back before the bullet is out but they stay straight until the barrel unlocks.
 
Scott Bear said:
I bet Newton would say they both start moving at the sametime. The slide would move slower because of its weight and the recoil spring resistance. The inertia might have to take longer to overcome the spring resistance?
Click to expand...

I bet Einstein would say that the Universe moves relative to the slide, barrel and projectile. How long this takes is... Relative.

Where to I apply for the position of "Gun Scientist"?
 
gwesson said:
It definitely moves before the bullet leaves the barrel. "SHE" cannot shoot her plastic-fantastic 9mm; it throws the point of impact to the left, indicating that the pistol is moving left before the bullet leaves it. If she locks wrists it shoots just fine for her - but she can only shoot ~7 shots like that before her wrists are done for the session... :(
Click to expand...

THIS has SFA to do with the recoil and everything to do with how SHE is holding the pistol. A poor grip or incorrect trigger pull can result in shots being thrown to one side or the other.
 
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