What force Moves the Slide ?

[MT1]

ok, So i just got done reading Jerry Kuhnausen principles of the 1911. Big question ? Without assuming what moves the slide after the bullet leaves the barrel and after reading Jerry Kuhnausen principles of the 1911. Don`t you think That the Head of the casing starts to push the slide rearward AFTER the casing Relaxes from being expanded for that millisecond. The casing Expands creates friction in the chamber wall then decides to move backward. I wonder if the extractor is even needed. There is no other force applying pressure to the slide other than the casing itself. So my question is if none of this is true what is creating the movement. ( AK47, gas block + expanded gas + piston = bolt carrier movement )

Interesting question. I've never given it much thought. I guess my confidence in John Browning's designs trusts he wouldn't add something that isn't needed.

Extraction is performed through the proper timing of slide inertia, the extractor holding the rim and the ejector kicking the case out. If you are curious to the need of the extractor, remove it and see how well your 1911 works (or doesn't).

[Grey Bearded One]

To clarify a few points above, don't confuse acceleration velocity, and momentum. Velocity is the speed at any given time.

If you want to go all technical, velocity is not the "speed" at any given time. Velocity is a vector and is the rate of change of position with respect to time. Speed is a scalar quantity that is the magnitude of velocity.

[indianjack]

So let me get this straight and please correct me where ever I'm wrong. The instant the power ignites it starts forcing the bullet forward, starts expanding the case outward against the barrel and backwards against the breech. Also it starts compressing a spring. Once the bullet has left the spring is compressed enough to complete the cycle of racking the slide and all that entails?

[gghbi]

So let me get this straight and please correct me where ever I'm wrong
.
The instant the power ignites it starts forcing the bullet forward, The bullet starts moving once enough pressure to overcome the case tension and then the deforming as it enters the rifling - not quite instantaneous

starts expanding the case outward against the barrel and backwards against the breech. OK

Also it starts compressing a spring. The spring is compressed by the rearward movement of the locked slide/barrel reacting to the explosion (expanding Gas)

Once the bullet has left the spring is compressed enough to complete the cycle The momentum of the slide moving rearward continues to compress the spring until it begins the return to battery. This is dependent on a number of factors as JDH lists in his post.(noted below)

of racking the slide and all that entails?

,.

If you think about it, you can see that various combinations of bullet weights and powders may not generation enough pressure, or vice versa, too much. Heavy spring rates (or light bullet / powder combo) may shorten a slide cycle to where it doesn't get all the way back and strip the next round, or with a low resistance or worn spring (or heavy bullet, +p load) the slide may move rearward too quickly, affecting accuracy and more importantly, carrying to much momentum and slamming the slide against the rear stop and doing damage to the gun.

[alpacaheat]

[ExFlyinguy]

Here's my theory

[Gunsnwater]

Interesting question. I've never given it much thought. I guess my confidence in John Browning's designs trusts he wouldn't add something that isn't needed.

Extraction is performed through the proper timing of slide inertia, the extractor holding the rim and the ejector kicking the case out. If you are curious to the need of the extractor, remove it and see how well your 1911 works (or doesn't).

In straight blowback the case head pushing back against the breach face pins the case to the breach face long enough for complete extraction and ejection without the need for an extractor. This action class limits the power of cartage that can be handled.

[Gun]

ok, So i just got done reading Jerry Kuhnausen principles of the 1911. Big question ? Without assuming what moves the slide after the bullet leaves the barrel and after reading Jerry Kuhnausen principles of the 1911. Don`t you think That the Head of the casing starts to push the slide rearward AFTER the casing Relaxes from being expanded for that millisecond. The casing Expands creates friction in the chamber wall then decides to move backward. I wonder if the extractor is even needed. There is no other force applying pressure to the slide other than the casing itself. So my question is if none of this is true what is creating the movement. ( AK47, gas block + expanded gas + piston = bolt carrier movement )

The slide is already moving rearward, along with the barrel while the case is obturating. This lasts a very short period of time and before the barrel unlocks from the slide. The force that pushes the bullet down the barrel is the same force that moves the slide rearward, but in the opposite direction. This force acts against the inside of the case head which is already up against the breech of the slide, so it can be considered as one object, until the case hits the ejector.

To clarify a few points above, don't confuse acceleration velocity, and momentum. Velocity is the speed at any given time. Acceleration is the change in velocity. momentum is weight x velocity.

Momentum is MASS times velocity.

If you want to go all technical, velocity is not the "speed" at any given time. Velocity is a vector and is the rate of change of position with respect to time. Speed is a scalar quantity that is the magnitude of velocity.

Velocity is a function of time, and is the rate of change of position with respect to a frame of reference.

[gghbi]

In straight blowback the case head pushing back against the breach face pins the case to the breach face long enough for complete extraction and ejection without the need for an extractor. This action class limits the power of cartridge that can be handled.

That's they way it is supposed to work, but in my wife's Beretta Bobcat 22 it does not do so reliably! Still trying to find the magic ammo that does!

[knight0334]

Recoil energy on nearly all non-gas operated semiauto firearms.

While the bullet may already be out of the barrel, and the gas pressure has dropped, the energy is still there. It just takes a little longer to overcome the tension of the springs, and any locking mechanism if present, to open the action.

Gas pressure actually helps hold the action closed on guns that use extractors. The case is merely a gasket, which at the moment of being fired, and for a short time thereafter, it expands and seals the chamber. That expansion causes the case to stick to the walls of the chamber, which while being "hooked" by the extractor, that tension helps hold the gun in battery until pressure has dropped, allowing the case to retracted a hair.

There are a very few guns that do use some of the chamber pressure to assist in operating the gun, namely the Beretta Bobcat and Tomcats. But most of the operation is still from the recoiling energy.