Brian Williams
Moderator Emeritus
What does this show or explain about lockup.
linky to where I found the image
http://whatsthecrack.net
linky to where I found the image
http://whatsthecrack.net
Hey Tuner, xray of 1911 firing
- Thread starter Brian Williams
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Princi
Member
Brian, what are my old eyes seeing at the end of the barrel? Does this 1911 have a barrel bushing or am I seeing the end of the barrel?
Do you have any idea how the X-Ray was taken? i.e. could it be a fake?
Do you have any idea how the X-Ray was taken? i.e. could it be a fake?
1911Tuner
Moderator Emeritus
X-Ray
Good picture, Brian!
It shows what I've been saying for years.
The bullet is almost at the muzzle, and the slide has moved just a little...probably about .090 inch here. Look closely at the upper lugs.
See the gap at the rear? That's a big clue that many don't understand. The barrel is being pulled forward by the bullet's friction in the bore while the slide is being pushed rearward by the equal/opposite forces that are at work on the bullet base, and the slide is pulling the barrel rearward with it. The lugs are engaged...front barrel lug faces to rear slide lug faces in a shearing action...and the breech is locked under those forces.
If you go read the original patents filed by Browning, it states plainly that the breech is locked under force as the bullet is transiting the barrel. I'll see if I can dig'em up and post it here. Pretty sure I've got it somewhere.
The gap at the rear of the barrel lugs make me believe that the photograph is genuine. Detail like that is usually overlooked in fakes.
Good picture, Brian!
It shows what I've been saying for years.
The bullet is almost at the muzzle, and the slide has moved just a little...probably about .090 inch here. Look closely at the upper lugs.
See the gap at the rear? That's a big clue that many don't understand. The barrel is being pulled forward by the bullet's friction in the bore while the slide is being pushed rearward by the equal/opposite forces that are at work on the bullet base, and the slide is pulling the barrel rearward with it. The lugs are engaged...front barrel lug faces to rear slide lug faces in a shearing action...and the breech is locked under those forces.
If you go read the original patents filed by Browning, it states plainly that the breech is locked under force as the bullet is transiting the barrel. I'll see if I can dig'em up and post it here. Pretty sure I've got it somewhere.
The gap at the rear of the barrel lugs make me believe that the photograph is genuine. Detail like that is usually overlooked in fakes.
MaterDei
Member
My comment is not as technical as Tuner's comment but it's just as accurate.
COOL!
COOL!
Jim Watson
Member
If you go to the site, there is another x-ray image of the gun and a bullet having left the barrel going through a rack of thin plates about a foot away. The slide is just starting back good, but nowhere near ejection.
I promise. I promise. I promise. I won't say that the explanation sounds absolutely right, but isn't quite correct.
One more time, Tuner. Take an old .45 barrel. Ream it out so it is larger than the bullet diameter, with just enough shoulder to support the case. Grease it good to eliminate any remaining friction. And fire the gun. Let me know what happens when there is no friction to drag the barrel forward.
Jim
One more time, Tuner. Take an old .45 barrel. Ream it out so it is larger than the bullet diameter, with just enough shoulder to support the case. Grease it good to eliminate any remaining friction. And fire the gun. Let me know what happens when there is no friction to drag the barrel forward.
Jim
1911Tuner
Moderator Emeritus
re:
Have already done that, Jim. The slide moved as usual.
Do the rope trick, jim. Do it over and over again, and watch what happens closely. It'll come to ya.
And the explanation is absolutely correct. Force forward equals force backward. Force...from the controlled explosion and expanding gasses...acts equally on the slide and the bullet. Whether locked breech or straight blowback matters not. It works exactly the same way.
Blowback:
Bullet<--{BANG}-->Slide
Recoil Operated:
Bullet<--{BANG}-->Slide&Barrel--[Barrel Linkdown Point]Slide--->
Have already done that, Jim. The slide moved as usual.
Do the rope trick, jim. Do it over and over again, and watch what happens closely. It'll come to ya.
And the explanation is absolutely correct. Force forward equals force backward. Force...from the controlled explosion and expanding gasses...acts equally on the slide and the bullet. Whether locked breech or straight blowback matters not. It works exactly the same way.
Blowback:
Bullet<--{BANG}-->Slide
Recoil Operated:
Bullet<--{BANG}-->Slide&Barrel--[Barrel Linkdown Point]Slide--->
OP
OP
Brian Williams
Moderator Emeritus
1911Tuner
Moderator Emeritus
Indeed it must. Try driving a bullet through a barrel manually from chamber to muzzle.
Inertia is a resistance to a force applied. In this case, the inertial resistance of the bullet's mass is miniscule compared to the frictional resistance offered by the bore.
Let me say that Mr. Keenan has what is likely the best general gun knowledge of any gunsmith that I've ever read or spoken to. It's just the recoil question that he isn't clear on...or specifically, what causes recoil...how it manifests.
Objects don't move unless they're forced to move. Force being the operative word...and that the force must be great enough to overcome the object's resistance to acceleration. Force accelerates the bullet and the slide at the same instant...in opposite directions. As soon as the bullet's frictional resistance is broken...so is the barrel's...and the barrel is free to move backward. The only thing that has the opportunity to make the barrel reverse directions is the slide...which has been forced to move away from the bullet. The bullet and the breechblock/slide are the action/reaction pairs. The barrel is just along for the ride.
Let's pretend that we're powerful wizards, and that we can cause the slide to disappear at the very instant that the primer sparks...before the powder is lit.
What will happen? Which direction will the barrel move? Backward? No. It will move forward.
To reduce the action/reaction issue to the simplest terms:
Pick up a 30-pound medicine ball. Hold it close to your chest, and shove it away from you as hard and as suddenly as you can. The ball accelerates in one direction, and you accelerate in the other. Did the ball's movement push you backward...or did the force that you imposed on the ball with your arms cause you to move?
Later, I'll explain the rope trick that I mentioned. If I can convince Jim to do it...it'll clear things up a bit.
1911Tuner
Moderator Emeritus
The Rope Trick
Wrap a length of rope around your right hand, and grip in in your left hand so that it can slip through.
The rope will represent the bullet. The gripping, left hand will represent the barrel. The wrist of that hand will represent the slide.
Pull in opposite directions, but not hard enough to cause the rope to slip. You now have an action/reaction pair of objects. The rope and your left hand. You also have a pair of forces. One on the rope and the other on your left hand. Action/reaction forces always come in pairs...even if there is only one origin for those forces. There are always two forces with any pair of action/reaction objects.
Gradually apply more force until the rope slips through your left hand, and you'll notice that as soon as the rope(bullet) slips in one direction...your left hand(barrel) will slip in the other...in the same direction as your left wrist(slide)...or in the direction that the force is compelling it to move.
So...As soon as the bullet begins to move through the barrel, the slide is pulling the barrel off the bullet...because they are being pushed in opposite directions from the "Ground Zero" of a small, controlled explosion that has occurred between them.
Do the rope trick over and over and over until you see it. Repeat: The instant that the rope slips through your hand, your hand will slip off the rope.
Simple...what?
Wrap a length of rope around your right hand, and grip in in your left hand so that it can slip through.
The rope will represent the bullet. The gripping, left hand will represent the barrel. The wrist of that hand will represent the slide.
Pull in opposite directions, but not hard enough to cause the rope to slip. You now have an action/reaction pair of objects. The rope and your left hand. You also have a pair of forces. One on the rope and the other on your left hand. Action/reaction forces always come in pairs...even if there is only one origin for those forces. There are always two forces with any pair of action/reaction objects.
Gradually apply more force until the rope slips through your left hand, and you'll notice that as soon as the rope(bullet) slips in one direction...your left hand(barrel) will slip in the other...in the same direction as your left wrist(slide)...or in the direction that the force is compelling it to move.
So...As soon as the bullet begins to move through the barrel, the slide is pulling the barrel off the bullet...because they are being pushed in opposite directions from the "Ground Zero" of a small, controlled explosion that has occurred between them.
Do the rope trick over and over and over until you see it. Repeat: The instant that the rope slips through your hand, your hand will slip off the rope.
Simple...what?
Ah, yes, the old rope trick. But it is still the momentum of the bullet moving forward that causes backward recoil, not the friction in the barrel causing pressure. So if you did try the frictionless barrel, what caused the slide to move? The pressure must have been close to nothing in the barrel once the bullet was out of the case.
Jim
Jim
1911Tuner
Moderator Emeritus
No, no, no! I never said that, Jim. Recoil comes from force exerted on the slide. The same force that moves the bullet also moves the slide. The bullet's forward momentum can't do anything to make the slide move backward. It's going in the wrong direction. Mass doesn't move unless it's forced to move. The only way the bullet could force the slide to move is by hitting it.
Force...and the lack of friction between the bullet and the barrel actually makes it easier for the slide to move. There's nothing fighting it besides its own inertial mass and that of the barrel. It works like a straight blowback with the bore reamed out.
I think I see where you're goin'...and it's a common misunderstanding to believe that the bulk of the recoil impetus is generated after peak pressure occurs...when about 95% of the recoil force...and probbly about 90% of the muzzle velocity comes in the first half-inch or less of bullet travel. Go and unscrew the barrel from a double-action revolver and fire it. You'll notice very little difference in felt recoil. Add ballast to the gun to bring the weight back up if you wish.
A better demonstration would be to lop a 12-gauge shotgun barrel off to the same length as a fired shell and shoot it. It's illegal, but guaranteed to black your eye if you put your face on the comb of the stock....even if you add enough lead to the stock to make it weigh the same as before the barrel amputation.
Since you won't do the rope trick...do the exercise with the medicine ball. What causes you to be pushed away from the ball? Is it the ball moving forward...or is it the fact that your arms exerted a force against you and the ball at the same time?
Mass requires force to make it move. Recoil is not a force. It's the reaction to a force applied.
Force is required to get it moving...and then it has momentum.
Kruzr
Member
Haven't we done this before? 
1911Tuner
Moderator Emeritus
A time or two...but we have a large time with it, dontcha know.
Look at the picture that Brian posted, Kruz. See the front barrel lug faces in contact with the rear slide lug faces?
From the looks of it, there ain't much vertical lug engagement on that old girl, either.
Looks like the barrel is ridin' the link, too.
1911Tuner
Moderator Emeritus
Patent Pending-1911
Pay particular attention to lines15-25 and lines 40-60.
http://patimg1.uspto.gov/.piw?docid...1=0984519.PN.%26OS=PN/0984519%26RS=PN/0984519
Pay particular attention to lines15-25 and lines 40-60.
http://patimg1.uspto.gov/.piw?docid...1=0984519.PN.%26OS=PN/0984519%26RS=PN/0984519
Kruzr
Member
I see. The slow motion one I saw that caught the bullet leaving the barrel and a rule under the slide showing nearly 0.10 movement of the slide told me it was pressure against the breech (same pressure that moved the projectile down the barrel) that started the slide rearward.
The JMB patent told me that the slide was designed to cycle via the conservation of momentum of the bullet. (After the "body was in motion")
Therefore, I think you're both right.
1911Tuner
Moderator Emeritus
Better go re-read it, m'fren...
Phyphor
Member
It's all good,
Let Tuner speak his wisdom,
Let Tuner speak his wisdom,
1911Tuner
Moderator Emeritus
Wisdom
Nah. Ain't any wisdom to it. I just understand the thing.
Just in case Kruzr is still up...
A. There can be no movement without force. Mass resists movement. It must be pushed or pulled. Otherwise, it stands still.
B. Without movement, there just ain't any momentum TO conserve.
C. The slide can't conserve momentum from the bullet. They're two different objects moving in opposite directions. The bullet is moving in the wrong direction to give the slide momentum. (How can you push something by moving away from it? If you need to push your car, you don't turn your back and run from it.)
D. Once the slide is moving, THEN it has momentum...the conservation of which keeps it moving after the bullet is gone and it has no outside force driving it. That same conservation of momentum is what keeps the bullet moving after it exits the muzzle...and has no outside force driving it.
Got it?
Nah. Ain't any wisdom to it. I just understand the thing.
Just in case Kruzr is still up...
A. There can be no movement without force. Mass resists movement. It must be pushed or pulled. Otherwise, it stands still.
B. Without movement, there just ain't any momentum TO conserve.
C. The slide can't conserve momentum from the bullet. They're two different objects moving in opposite directions. The bullet is moving in the wrong direction to give the slide momentum. (How can you push something by moving away from it? If you need to push your car, you don't turn your back and run from it.)
D. Once the slide is moving, THEN it has momentum...the conservation of which keeps it moving after the bullet is gone and it has no outside force driving it. That same conservation of momentum is what keeps the bullet moving after it exits the muzzle...and has no outside force driving it.
Got it?
Kruzr
Member
In "Fisicks Skool", one of the "classic" examples of the third law of physics....which is the conservation of energy, momentum, and angular momentum, is the cannon firing the tennis ball.
The same momentum that the tennis ball has exiting the cannon is transferred back to the cannon in the opposite direction. Since the mass of the cannon is much greater than the tennis ball, the velocity is slower going backwards.
For every action, there is an equal and opposite reaction. When a gun fires, the momentum from the moving bullet is transferred back to the gun. If the gun is being restrained and friction exists, the momentum must go somewhere.......Mr. Newton said so.
The same momentum that the tennis ball has exiting the cannon is transferred back to the cannon in the opposite direction. Since the mass of the cannon is much greater than the tennis ball, the velocity is slower going backwards.
For every action, there is an equal and opposite reaction. When a gun fires, the momentum from the moving bullet is transferred back to the gun. If the gun is being restrained and friction exists, the momentum must go somewhere.......Mr. Newton said so.
1911Tuner
Moderator Emeritus
Kruzr...Sorry buddy. Saying that the gun recoiled because the bullet moved is like saying that the bullet moved because the gun recoiled. Same difference.
Read it one more time...
Mass obeys Newton and tries to remain at rest until an outside force overcomes its resistance and causes it to move.
Once it's moving, it has momentum.
Bullet acceleration results from force. So does recoil. In every action/reaction event, there must be two interacting objects and two forces.
Read it one more time...
Mass obeys Newton and tries to remain at rest until an outside force overcomes its resistance and causes it to move.
Once it's moving, it has momentum.
Bullet acceleration results from force. So does recoil. In every action/reaction event, there must be two interacting objects and two forces.
HammerBite
Member
The slide (locked-together barrel and slide) is being pushed backward by the same pressure that is pushing the bullet forward. The bullet goes one way and the barrel-slide goes the other. If you do the math you find out that the forward momentum of the bullet is balanced by the backward momentum of the slide-barrel. The center of gravity of the slide-barrel, with the bullet in it, remains stationary. The momentum of the slide barrel is conserved; it starts out zero and remains zero. At least it tries to. As soon as the recoil spring starts to compress it becomes an unbalance external force and conservation of momentum no longer applies to the barrel-slide.
Friction does not cause the bullet to pull the barrel forward, it only slows things down. If the bullet pulled the bullet forward the gun wouldn't recoil backward; it would pull you forward.
1911Tuner
Moderator Emeritus
Hammer...You've almost got it!
This statement...
...is absolutely correct.
This one...
...is a little short, I'm afraid.
The frictional contact between the bullet and the barrel is high. Try driving a bullet through to get an idea of how high that is. If the bullet is being forced through the barrel from behind, it has to hold the barrel forward. Go back and look at the locking lugs in Brian's picture. See the gap at the rear faces of the barrel lugs? The barrel is forward as far as it can go, and the slide has been driven rearward.
Because the bullet is moving, the frictional resistance is falling...and the faster it moves, the lower the frictional force becomes. Ever notice how much easier it is to keep a heavy object sliding across a floor than it was to get it moving in the first place? This also explains why a bullet continues to gain velocity after peak pressure. It simply requires less force to accelerate it than it did to get it going in the first place. The pressure peak occurs quickly and falls off quickly because of the increasing volume of the cylinder behind the bullet.
This statement...
...is absolutely correct.
This one...
...is a little short, I'm afraid.
The frictional contact between the bullet and the barrel is high. Try driving a bullet through to get an idea of how high that is. If the bullet is being forced through the barrel from behind, it has to hold the barrel forward. Go back and look at the locking lugs in Brian's picture. See the gap at the rear faces of the barrel lugs? The barrel is forward as far as it can go, and the slide has been driven rearward.
Because the bullet is moving, the frictional resistance is falling...and the faster it moves, the lower the frictional force becomes. Ever notice how much easier it is to keep a heavy object sliding across a floor than it was to get it moving in the first place? This also explains why a bullet continues to gain velocity after peak pressure. It simply requires less force to accelerate it than it did to get it going in the first place. The pressure peak occurs quickly and falls off quickly because of the increasing volume of the cylinder behind the bullet.
Jim Watson
Member
The slide (and whole gun) has to "conserve" momentum by moving in the opposite direction from the gun. Momentum is a vector quantity and is not completely described without specifiying direction. A loaded gun at rest has no momentum, and the gun+bullet system as a whole will continue to have no overall momentum. Fire the bullet north, the gun recoils south with the same momentum so as to leave zero total momentum.
Things like barrel friction and gas pressure are the means by which forces are applied to transfer that momentum. And Mr Browning et al use them to make the guns work.
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