does the bullet exit before the slide moves?

[Koda]

If it exited AFTER the slide moved you couldn't hit a trashcan from 5 feet away without a fixed barrel!

That would only be true if the bullet exited the barrel after the barrel disconnected from the slide. This is why the slide and barrel remain locked together for a short time.

 

[Koda]

The slide and barrel start moving at the same time the bullet does and for the same reason. A force is being applied to it. It's just so much more massive than the bullet that it doesn't move nearly as fast and therefore doesn't move very far in the time the bullet is in the barrel. The link does not hinder the movement of the slide. It keeps the barrel and slide locked together during the amount of time it takes for the bullet to leave. The slide and barrel both move, just locked together. After the locked together barrel/slide combination has moved a short distance, then the link pulls the barrel lugs out of engagement with the slide and lets the slide move on from the momentum gained in the initial acceleration. If you believe the slide sits totally motionless during the bullet's trip down the barrel, you're not looking closely enough. If you think it waits (as opposed to moving, just much slower than the bullet) I would ask how do it know to do dat?

This makes sense, I like it.... Thanks for explaining this.

 

[Fast Eddie]

That Browning guy was a genius.

 

[Basedgreaser]

No doubt! Either JMB got very lucky, or he spent a little time sorting it out. It sure seems like the bullet is long gone and there would not be enough pressure left to run the slide. Shows what I know...

Its not entirely about pressure, energy transfer is more or less the goal, think about say a slow mo of bruce lee punching someone, even though his fist pulls back, you will keep seeing the skin and tissue ripple as the person he punches absorbs the blow even after his fist is no longer in contact with the target

 

[Lilhigbee]

The slide and barrel start moving at the same time the bullet does and for the same reason. A force is being applied to it. It's just so much more massive than the bullet that it doesn't move nearly as fast and therefore doesn't move very far in the time the bullet is in the barrel. The link does not hinder the movement of the slide. It keeps the barrel and slide locked together during the amount of time it takes for the bullet to leave. The slide and barrel both move, just locked together. After the locked together barrel/slide combination has moved a short distance, then the link pulls the barrel lugs out of engagement with the slide and lets the slide move on from the momentum gained in the initial acceleration. If you believe the slide sits totally motionless during the bullet's trip down the barrel, you're not looking closely enough. If you think it waits (as opposed to moving, just much slower than the bullet) I would ask how do it know to do dat?

Ah, someone who understands physics. You are a rarity sir!!

 

[The Heretic]

If you mean moving in relation to the rest of the gun, then generally no. Most pistols have the barrel locked until after the projectile leaves the barrel, and that prevents the slide and barrel from moving (in relation to the rest of the handgun).

Should the barrel and slide move too soon (before the projectile leaves the barrel), then there is a good chance pressure in the barrel would exhaust from the breech and this is highly undesirable, both from a safety and functional point of view, so usually most semi-auto handguns are designed to not let this happen.

 

[Ownerus]

If you mean moving in relation to the rest of the gun, then generally no. Most pistols have the barrel locked until after the projectile leaves the barrel, and that prevents the slide and barrel from moving (in relation to the rest of the handgun).

Well, sorta but not quite. Recoil operated guns are basically 3 components. The barrel, the breech block, and the frame. At the moment of firing, the barrel is locked to the breech block (usually in the form of the slide). The locked-together barrel and breech block are slide-ably mounted on the frame. They are free to move under the influence of the recoil force against inertia and the force of the recoil spring.

You can test this by pushing on the end of the barrel OF THE UNLOADED GUN!! The barrel and slide will move easily relative to the frame against just the force of the recoil spring. In the case of a Browning style lockup (which is nearly everything anymore) the barrel and slide will move a short distance. In less than the time it takes for the heavy slide/barrel combination to move that short distance, the bullet has exited the barrel. They then continue on rearward until the link or cam surface drops the rear of the barrel and disengages the locking feature. The slide can continue on rearward, coasting under the momentum it gained in the initial acceleration to complete the cycle.

 

[Dapapadon]

Well, sorta but not quite. Recoil operated guns are basically 3 components. The barrel, the breech block, and the frame. At the moment of firing, the barrel is locked to the breech block (usually in the form of the slide). The locked-together barrel and breech block are slide-ably mounted on the frame. They are free to move under the influence of the recoil force against inertia and the force of the recoil spring.

You can test this by pushing on the end of the barrel OF THE UNLOADED GUN!! The barrel and slide will move easily relative to the frame against just the force of the recoil spring. In the case of a Browning style lockup (which is nearly everything anymore) the barrel and slide will move a short distance. In less than the time it takes for the heavy slide/barrel combination to move that short distance, the bullet has exited the barrel. They then continue on rearward until the link or cam surface drops the rear of the barrel and disengages the locking feature. The slide can continue on rearward, coasting under the momentum it gained in the initial acceleration to complete the cycle.

The Heretic had it closed than you. There is no rearward recoil to speak of till the projectile leaves the barrel. When the primer ignites the propellant pressure builds in the chamber and pushes against the breach, barrel and bullet. The breach and barrel are locked together with the locking lugs. The bullet is free to move, we'll leave out the case crimp, it is minimal to the pressures involved. So the pressure from the propellant is building and pushing the bullet down the barrel. The rearward recoil is minimal because the propellant is pushing against the breach and the bullet. The mass of the barrel and breach are many times the mass of the bullet. But the pressure is high, 35,000 psi for a 9mm. Once the bullet leaves the end of the barrel that pressure is now escaping the end of the barrel. These escaping gasses are the recoil that operates the slide. Pushes back on the barrel and slide, unlocks the lugs, the barrel cams down, slide continues rearward... You get the picture. The gasses escaping the end of the barrel is the recoil.

 

[IronMonster]

Gun go boom

 

[Andy54Hawken]

What is this "Slide" that folks are speaking of?.....
Just kidding... good question and some good answers.
Andy

 

[nwwoodsman]

whats interesting to me is how they figured this precise timing out back in 1911?

It was actually closer to 1899. It did not become known as the "1911" until it was put into military service.

 

[Ownerus]

..... There is no rearward recoil to speak of till the projectile leaves the barrel. When the primer ignites the propellant pressure builds in the chamber and pushes against the breach, barrel and bullet. The breach and barrel are locked together with the locking lugs. The bullet is free to move,.....

The force acting on the bullet is also acting on the breech face. Remember, "for every action there is an opposite and equal reaction". The bullet is free to move. So is the barrel and slide. They are locked together. They are not locked to the frame. They move at the same time as the bullet and for the same reason. Just not as far or as fast because of their greater mass.

The gasses escaping the end of the barrel is the recoil.

The mass of the escaping gasses is the mass of the powder. The 6-7 grains of powder gas has an effect but nothing compared to the mass of the bullet.

 

[EPS]

It was actually closer to 1899. It did not become known as the "1911" until it was put into military service.

That 's the right answer

 

[Argonaut]

That Browning guy was a genius.

That western (Utah) Mormon guy from a polygamist family was pretty bright for sure.

 

[Dapapadon]

The force acting on the bullet is also acting on the breech face. Remember, "for every action there is an opposite and equal reaction". The bullet is free to move. So is the barrel and slide. They are locked together. They are not locked to the frame. They move at the same time as the bullet and for the same reason. Just not as far or as fast because of their greater mass.

I didn't say rearward force was zero, I said it is minimal. Let's use a Glock 17 with a 115 grain bullet as an example. I'll use 1 pound as a conservative weight of the barrel and slide, or 7000 grains. Even though the barrel and slide are not locked to the frame they are resisted from moving rearward by the recoil spring. The spring force is measured in pounds. So if just 2 pounds of force are holding the barrel and slide forward that is another 14000 grains.
So the weight of the barrel and slide, 7000 divided by the weight of the bullet, 115 is 60.869. The barrel and slide are 60 times the mass of the bullet. If we add the 2 pounds of spring force to the weight of the barrel & slide we get 3 pounds or 21,000 grains. Divide that by the weight of the bullet, 115 we get 182.608. The rear resistance of the barrel, slide and recoil spring is 182 times the weight of the bullet. I will note here that the 2 pound force of the spring is greater than the weight of the Glock frame and an empty magazine. Just saying.

You can watch slow motion internet videos that show the barrel & slide don't start to move rearward till the bullet leaves the barrel. That Myth Busters video is misleading. You can see blow by gasses leaving the barrel ahead of the bullet. The barrel & slide start to move rearward as those gasses leave the barrel.

The mass of the escaping gasses is the mass of the powder. The 6-7 grains of powder gas has an effect but nothing compared to the mass of the bullet.

Wow, not sure what to say here. Short and simple answer is the powder charge is ignited by the primer. As the powder burns it releases energy. That release of energy in the form of pressure is what propels the bullet. In ballistics labs (way over my head) they calculate powder charges. I don't think they ever use the weight of the powder charge verses the weight of the bullet. It would be he energy released by the burning of the powder verses the bullet weight.

I researched this years ago to get a basic understanding of ballistics. I did a little more research last night. As a general rule only 30% of the peak pressure remains when the bullet exits the barrel. Of a conservative 30,000 psi peak pressure for 9mm only 1000 psi would exhaust out the end of the barrel when the bullet leaves. This 1000 psi exhausting out the end of the barrel is the "recoil" that operates the slide of a semi-automatic handgun. Also that 1000 psi exhausting is the action Newton referred to and the reaction is the slide cycling, extracting the spent case then picking up and chambering a new round.

You can research internal ballistics to get a better understanding of what happens before the bullet leaves the barrel.

 

[EPS]

They make compensaters for 1911 that are actually the barrel bushing so yes the bullet leaves the barrel before the slide moves

 

[EPS]

 

[Koda]

Bushing comps dont actually do anything....

 

[EPS]

Bushing comps dont actually do anything....

I didn't say they work lol unless you have a long barrel with comp then they might do something other wise there just for looks lol I like the way they look but it adds a inch or so to your gun

 

[Koda]

What I meant was the bushing comp doesnt validate if the bullet leaves the barrel befor the slide moves.

Im going with some of the excellent replies back in this thread indicating the slide moves with the bullet just not enough to measure.