Hey Tuner, xray of 1911 firing

[SDC]

Nope. Not at all. What I am suggesting is that you can press two objects together with enough force that it's extremely difficult to pull them apart at 90 degrees to the direction of that force...which is how the barrel disengages from the slide...vertically.

That (slightly restated) IS the Blish principle, something which doesn't actually exist. Blish said that he believed that this theory "worked" best when two dis-similar metals were used, but experiment after experiment has failed to show that it has any basis in reality.

So, now you're trying to use a completely different set of dymics into the argument in order to support your beliefs?

Not at all, I'm just using it as a similar example to point out that your argument doesn't make sense. If "bullet pull" was as crucial to the operation of a 1911 as you seem to believe, then it should produce a measurable effect in that operation. The trouble is, it doesn't. The pistol unlocks the same way and at the same point in slide travel when you fire it with live ammo as it does when you cycle it by hand.

 

[Peter M. Eick]

Reading this over, I am surprised that no one has done up a full blown 3D computer model of the 1911 in operation.

That would make a really interesting PhD dissertation on exactly the forces involved in making a 1911 run and then have computer simulations that allow one to adjust the dynamics of the model.

I think this is the only way that these questions could be solved for most folks. I say most because some will always argue the simulation does not represent reality.

 

[1911Tuner]

Blish!

That (slightly restated) IS the Blish principle, something which doesn't actually exist.

Not really. Let's try yet another hypothetical...

Attach a cable to a quarter-inch steel plate, 1 foot square. Lay the plate on top of a steel block that weighs 1440 pounds. Place an identical steel block on top of the plate. You now have a force of 10 pounds per square inch on the plate. Do you believe that you can pull the plate out from between the blocks by pulling on the cable...using only the force that your body can apply?

Assuming again that the barrel is indeed held forward and the slide is moving rearward...and the locking lugs are engaged horizontally in a shearing fashion...there is 20,000 pounds of force per square inch bearing on the lugs at the instant of peak pressure.

Assuming that the total surface area of the lugs is roughly a half inch square...there is an opposing force on the lugs equal to 5 tons.

Let's try another one...using a simple bolt-action rifle.

.308 caliber...52,500 CUP, which works out to about 57,000 pounds psi at peak. If you were fast enough...and could time it perfectly...do you believe that you could lift the bolt and unlock the breech at the precise instant of peak pressure?

Do you believe that poor little link could pull the barrel out of engagement with the slide...at the precise instant of peak pressure? Even at 10% of the peak pressure...when the bullet is about to clear the muzzle...there's still a thousand pounds of opposing force on the lugs.

You don't need to believe in the Blish principle to know that it would be impossible. Newton's laws will do.

 

[JohnKSa]

If you've used layout fluid on the barrel lug faces....front...you'd see ink removed from the faces, indicating contact with the rear faces of the slide lugs.

In other words, wear/damage to the front faces of the barrel lugs can happen without any barrel/bullet friction as long as any significant impulse type force is directed against the breechface. Barrel/bullet friction is not necessary to account for the effect seen in the X-Ray pic.

Because nothing CAN move.

In other words, the chained blocks provide a very poor analogy for the 1911 system. Essentially there's no analogy for the chain whether it's taut or loose at the beginning of the experiment.

BTW, the revolver analogy (stretched frames) is a poor analogy as well. The stretching is due to the actual impact of the bullet on the forcing cone--which can generate enough force to split the cone in the extreme case. If it were due to bullet/barrel friction we would see stretched autopistol barrels and stretched rifle barrels.

 

[SDC]

Not really. Let's try yet another hypothetical...

Attach a cable to a quarter-inch steel plate, 1 foot square. Lay the plate on top of a steel block that weighs 1440 pounds. Place an identical steel block on top of the plate. You now have a force of 10 pounds per square inch on the plate. Do you believe that you can pull the plate out from between the blocks by pulling on the cable...using only the force that your body can apply?

No, but we're not discussing what MY BODY can do, remember? The issue is whether or not this supposed "bullet pulling" force plays any part in the operation of the pistol, and I haven't yet seen any evidence that it does. I would be very interested in seeing an experiment performed along the lines of my earlier suggestion, however (a barrel minus the lugs, so it'll work as a straight blowback).
How about a practical experiment that I have actually TRIED? I don't know if you've ever seen a Richardson Guerilla Gun, but they're basically a "factory-made zip gun", sold after WW2 (Ilits Richardson was a USN lieutenant who saw Filipino guerillas using these things against the Japanese, and figured he could sell plenty of them after the war). These shotguns are simply open tubes (12 gauge size) that slide into another tube that's bolted onto a simple stock, and the rear tube has a fixed firing-pin that fires the shell when the front tube/barrel is pulled backwards into it. A typical 12-gauge shell produces MANY THOUSANDS of pounds of pressure when it fires, and that pressure is trying to blow the front and rear tubes apart, yet I have no difficulty at all holding that barrel closed during firing, simply because the pressure is gone so fast that it's not sustained for any amount of time. The same thing happens with this mystical "force" that you claim is pulling the barrel forward.

 

[1911Tuner]

Are you two smokin' the same...tobacco?

I can't help'em, Brickeyee. See if you can find the words.

 

[peterotte]

Hi there all.

Although I think the inertial impulse force is the greater, I would suggest that the impulse force of the bullet striking the rifling, together with the torque reaction vector is quite considerable. I would also suggest that the bullet friction during it's passage through the barrel is much lower than one might think but still quite significant. All these factors (at which we are all just guessing, at least, I am) simply infuence the required spring force and slide mass to keep the pistol cycling in proper ballance. Removing the locking lugs would necessitate a much heavier slide and stronger spring, otherwise, the breach would open way too soon, and and strike the slide stop way too hard, whatever the force mechanism is.

Peter

 

[brownie]

"that pressure is trying to blow the front and rear tubes apart"

Well, the frame and outer tube would certainly be pushed backwards, but since the inner tube, the "barrel", is the same diameter as the shot column and has no rifling, there will be little or no friction between the shot column and the barrel and, therefore, little, if any, forward force exerted on it. Your experience firing it is what I would expect.

--Bill

 

[1911Tuner]

peterotte...Sorry. The laws of physcis have been suspended until further notice...

 

[ClarkEMyers]

Would it were not so - I'd like a .460 Rowland but......

Would it were not so - I'd like a .460 Rowland but stretching the slide until it cracks worries me a whole lot more than pressure on the breech face or stopping the slide in recoil on the bowtie area or maybe a buffer or two.

The M1894
[that's the year folks and the jump from this to Browning's designs shows some of the genius of JMB]
Steyr Mannlicher Blow-Forward, Semi-Automatic Pistol
This earliest Steyr Mannlicher pistol, manufactured by FAB.D'ARMES Neuhaussen, Switzerland, was designed to be self loading and to use a special rimmed cartridge in 6.5 mm caliber. The design represented an entirely new utilization of mechanical principles in automatic action called "blow-forward action". In the standard type of automatic action for low powered cartridges, the recoil (or blow-back) is utilized to drive back a movable breech face or block, Mannlicher utilized the principle of a rigid standing breech with the barrel blowing forward to extract, eject, and prepare for reloading. The blow-forward principle has been utilized in very few firearms.

A special barrel housing which carries the sight covers the entire length of the barrel (6.49 in/165 mm) when the arm is closed. A heavy recoil spring is mounted concentrically around the barrel within this housing and is compressed between a shoulder at the forward end of the casing and a shoulder at the rear of the barrel.

United States Patent 5123329
Abstract:The present invention comprises a self-actuating blow forward firearm having a fixed breech block located to the rear of the firearm. A cartridge feeder provides a supply of cartridges to the loading area so that the firearm can be used as an automatic or semi-automatic weapon. The firearm also contains an outer receiver tube and a movable inner gun barrel which is biased toward the rear of the firearm by a spring disposed in a chamber between the receiver tube and the inner movable barrel. When the trigger mechanism is activated, the action of the bias spring causes the inner movable barrel to move backward toward the breech block striping a cartridge from the feeding device and forcing the end of the cartridge against the firing pin on the breech block. The bullet is fired down the bore of the inner movable barrel. The movement of the bullet along the bore of the inner movable barrel drags the barrel forward against the action of the bias spring. The addition of a piston device attached to the muzzle end of the inner movable barrel causes added momentum to be delivered to the moving barrel to assist the barrel in its forward movement. This added momentum can be further enhanced by including a muzzle brake adjacent the piston device. The battering of the various parts of the firearm and the cycle speed of the firearm can be reduced by use of an air pressure chamber situated between the inner movable barrel, the receiver tube, the barrel guide and a shoulder on the inner movable barrel.

 

[presspuller]

peterotte...Sorry. The laws of physcis have been suspended until further notice...

Some things is like trying to teach a pig to sing, you waste your time and annoy the pig.

 

[1911Tuner]

Blow-Forward

Excellent post, Clark...but you probably wasted your time. At this point, I don't think they'd believe it if John Browning himself explained it.

 

[JohnKSa]

I think if you re-read my post you'll see that I'm not saying that there isn't any bullet/barrel friction effect, just pointing out that it's not necessary to explain wear on the front of the barrel locking lugs.

As far as the two block example, it's an interesting physics experiment--I just don't see the application to this topic.

 

[1911Tuner]

I'm not saying that there isn't any bullet/barrel friction effect, just pointing out that it's not necessary to explain wear on the front of the barrel locking lugs.

Yes it is, John. You just haven't throught it through. How can the slide pull the barrel rearward if it doesn't have some mechanical connection to pull it WITH? What is that mechanical connection? Go look at the X-ray. The front faces of the barrel lugs are clearly being pressed against the rear faces of the slide lugs....AND...because there is a signifigant FORWARD drag on the barrel by the BULLET...it's pulling that barrel backward against resistance...against a force that is trying to push it forward...whether or not you want to believe it.

As far as the two block example, it's an interesting physics experiment--I just don't see the application to this topic.

Just trying to illustrate how the more massive slide can pull the less massive barrel rearward once things get moving. First, they have to be ABLE to move.
Once momentum is established, the heavier object will overcome the lighter one's resistance and cause it to change direction. If the chain is taut...and the force applied isn't large enough to snap the chain...nothing CAN move...so nothing DOES. If nothing moves, there is no momentum. None. Zip. Nada.

Because...

Momentum is the product of mass times velocity. The mass has to move before momentum is established. Mass doesn't move unless a force is imposed on it. The bullet can't push the slide backward by moving forward.
It's travelling in the wrong direction to push the slide. (It is, however, imposing a forward drag on the barrel.) The push comes from the force vector that is operating between the two objects. The bullet merely provides a resistance for the force to push off of...the same as the slide does for the bullet.

Say goodnight John...

 

[JohnKSa]

Come on Tuner, you admitted earlier on the thread that the results of my punch experiment would result in wear to the front of the locking lugs with absolutely nothing touching the barrel. The inertia of the barrel is sufficient resistance.

The barrel clearly also has inertia when the gun is fired and therefore the locking lugs will show wear from the firing process (just as from the punch experiment) even if it were possible to completely eliminate the bullet/barrel friction.

Just trying to illustrate how the more massive slide can pull the less massive barrel rearward once things get moving.

The slide and barrel are a single unit at the moment of firing due to the locking mechanism, therefore they move together.

The bullet can't push the slide backward by moving forward.

Wow. Nope, that's all--just "Wow".

Goodnight John.

 

[peterotte]

1911Tuner

peterotte...Sorry. The laws of physcis have been suspended until further notice...

Nope - they have not.

Just trying to illustrate how the more massive slide can pull the less massive barrel rearward once things get moving. ......
..... The bullet can't push the slide backward by moving forward.
..... The bullet merely provides a resistance for the force to push off of....

Nope.

The gasses acting against the rear of the case push the case back which in turn pushes the slide back which in turn pulls the barrel back which in turn is being held forward, largely by inertia. And this is Newtonian physics.

Simply put - Force = Mass X Acceleration

The slide is acceleration the barrel rearward
The barrel has mass
Therefore, a force is exerted on the locking lugs of the barrel.

If you can give me the weight of the slide, the weight of the barrel and the weight of the bullet - we know the muzzle velocity of the bullet, then I will do the math and show you how it works. I will also show you the forward drag of the bullet, the forward impulse of the bullet entering the barrel as well as the forward force vector from the torque reaction of the bullet being angularly accelerated. It will take me a few days 'though.

Regards
Peter

 

[1911Tuner]

Nope - they have not.

That was a wry attempt at sarcasm. Maybe I should've included a simile.

The gasses acting against the rear of the case push the case back which in turn pushes the slide back which in turn pulls the barrel back which in turn is being held forward, largely by inertia. And this is Newtonian physics.

Simply put - Force = Mass X Acceleration

The slide is acceleration the barrel rearward The barrel has mass
Therefore, a force is exerted on the locking lugs of the barrel.

That's what I've been saying all along...but you've forgotten one resistive force...and it's larger than the barrel's inertial resistance. I'll let ya think about it.

 

[1911Tuner]

Wore Plumb Out

I'm tired of arguing the same points...so I'll just put up a few facts and let everybody figure it out for themselves. This is a little involved, and it took some time to write. All I ask is that everyone pay me the courtesy of reading it through...carefully.

Review Newton 1 and 3. They'll help. Newton 2 is a little less helpful, but go ahead and look at that one too if you like. It's related.

The straight blowback operation is simple. Force on the bullet and force on the slide pushes each in opposite directions. Any argument? No? Good.

The locked breech design works the same way. Powder burns...Gasses expand..Pressure builds...Force on the bullet pushes it through the barrel...Force on the slide pushes it rearward.

The only difference...The ONLY difference...is that in the blowback, the slide moves independently of the barrel, while with the locked breech pistol, the slide snags the barrel on its way rearward and drags it along with it. Because the barrel has mass...the slide has to overcome that. Because the two are mechanically connected, the are...for all practical purposes...one part. So, until the barrel reaches the linkdown point, the slide's mass is roughly 40% greater than it is AFTER the barrel drops. This added mass slows the slide's acceleration...giving the bullet more time to reach the muzzle. Breech opening is thus delayed. It's very nearly a delayed blowback operation...but because the slide doesn't move independently of the barrel...we have to call it locked breech.

But the barrel's mass isn't the only resistance that delays the slide. There's another, more powerful force at work...the one we've been fighting about.

The bullet is a tight fit in the barrel. Any argument? You! There...in the back. Go push a bullet through a barrel with a stick and report your findings.

Because the bullet is a tight fit...and because it stays in contact with the barrel's inner surface for the whole trip...it transfers a frictional force to the barrel in the direction that it...the bullet...is moving. Namely forward. The bullet doesn't shrink, and the barrel doesn't expand to any practical degree, so the force remains in effect as long as the bullet is in the barrel and moving forward.

Because there is a forward force on the barrel, we have to factor it in. Don't believe it's signifigant? Install a 6-inch Longslide barrel in a Commander. Lock the gun in a vise. Grab the end of the barrel and pull it forward while a friend pulls on the slide.

We have another resistive mechanism. The recoil spring. We can agree that the recoil spring doesn't provide very much resistance during 1/10th inch of compression...until we remember that, in a 5-inch pistol with a standard 32-coil/16-pound spring...there's about 4.5 pounds of preload before anything even moves. So...bearing in mind that any resistive force will become more resistive the faster and harder that we try to accelerate it...that 4 pounds of resistance will multiply.

And there is yet another one. The spring also has mass. Gotta move that, too...and the faster and harder you push on it...the harder it fights.

These last two are operating in both the blowback and the locked breech pistol. I included them to provide SD with a clue so that he can figure out why the gun moves before the bullet exits the bore...and there's one more mechanism that contributes to that. I'll leave it to him to find it. Happy huntin' m'fren.

Finally...Nothing can be discounted when trying to understand the reality. Nothing. Anything that has the opportunity to delay the slide's movement WILL delay it. Anything that CAN resist it...WILL resist it. Resistive force comes in three forms. Inertial...provided by the mass of the object. Frictional force...provided by the object's contact with anything else. Mechanical obstruction. The proverbial brick wall.

We can't see force. We can only see its effects. That we can't see it doesn't prove that it doesn't exist. The barrel can't actually be pulled forward very much...if at all...because there are mechanical obstructions blocking it. The most obvious is the slidestop pin to lower barrel lug contact. Less obvious is the locking lug engagement within the slide...which is being driven rearward. BUT...just because we can't see the barrel move is not proof that the force on it isn't there. If you push on your house, you can't move it...but the force is still there...pushing on the house. While the bullet is moving thought the barrel...it's transmitting a forward force TO the barrel...even though the barrel can't move forward. It thus becomes a resistive force for the slide...and the faster the slide moves, the harder this force works against it.

To wrap it up...I hope that by now, we're all in agreement that mass requires force to set it into motion...and that the bullet can't generate a directional force to the slide while it's moving away from it. There must be a force vector between the two...and that force must be an unbalanced force. That is...the force must be greater than the resistance offered by the object that it's trying to move. When the force is balanced...force and resistance are equal...we have equilibrium. One cancels out the other, and nothing moves. Only when the force is unbalanced do things start moving. Only when things move do we have momentum.

Now...I'm a busy man. I've got 14 dogs to tend to, and about another 200 pounds of lead that I'm tryin' to turn into bullets. Figure it out.

John...My offer still stands. If you're ever in my neck of the woods...Turbocoffee, bullets and barbecue are on me.

 

[brownie]

Tuner,

Nice, concise exposition. Had I not already agreed with you, I would now.

--Bill

 

[presspuller]

Tuner,

Nice, concise exposition. Had I not already agreed with you, I would now.

--Bill

What he said.

 

[Grump]

I'm not gonna read this whole thread, but Tuner, if that forward friction thing is SOOO huge, and the bullet's movement don't cause the recoil, then howcome my revolvers and bolt guns recoil too?

I recall something about "total mass of recoil ejecta" being the thing to consider in calculating recoil. Explains why my 125-gr bullets with 2X.X grains of WW296 kick just as hard as 146-gr bullets with 9.whatever Unique (or whatever the load was) at the same velocity. But aren't lighter bullets supposed to kick less? Yeah, but the bullet plus powder charge weighed the same.

I thought recoil forces were being applied to the launch platform long before those forces could overcome inertia and commence perceptible movement.

 

[DBR]

Tuner, nice explanation:
The "other significant force", leaving aside minor forces, would be the firing pin stop engaging the hammer to re-cock it and the subsequent compression of the main spring. This is actually a significant force re the unlocking time. This occurs almost immediately when the slide tries to move backward and its effect is probably over before the bullet leaves the barrel.

 

[1911Tuner]

if that forward friction thing is SOOO huge, and the bullet's movement don't cause the recoil, then howcome my revolvers and bolt guns recoil too?

Lemme see if I can find the words to explain it...

When the bullet moves through the barrel in one direction, the barrel can also slip backward. Frictional resistance doesn't mean that it can't move. Only that its movement is resisted.

You may be better able to see it if you try this: I call it the rope trick.

Wrap a length of rope around your right hand, and grip the rope with your left hand. Pull against the rope in opposite directions with gradually increasing force...until the rope slips. Watch closely. When the rope slips through your hand in one direction...your hand slips off the rope in the opposite direction. This is action/reaction. You may need to do it several times before you realize what you're watching...but you'll eventually see it.

That's why the guns recoil SOOOO hard.

Because...

When the bullet moves forward, the barrel can move backward...so that when the force that bears against the breechblock...bolt face...recoil shield...or the closed breech of a smoothbore musket...that force shoves the gun backward. Because the barrel is attached...it goes whichever direction that the receiver goes.

The "other significant force", leaving aside minor forces, would be the firing pin stop engaging the hammer to re-cock it and the subsequent compression of the main spring.

You've got it!

When the slide bears against the hammer, it exerts a linear force that transfers to the frame of the gun...rolling the muzzle upward while the bullet is still fightin' its way to open air.

 

[peterotte]

Hi there 1911Tuner

Please don't misunderstand me. I too should have added the smiley. I am being sincere about doing the math. I really do not know the mass of the slide and barrel. And I really do want to see the extent of the frictional force. And yes, the barrel expansion may be insignificant and therefore the 'friction reducing effect' may be minimal. But I suspect that it is more than one might think. (That math I can do too - if someone would be kind enough to tell me the barrel dimensions).

And if I may add - thanks for keeping the discussion lively!

Regards
Peter

 

[peterotte]

Hi Grump

There are three recoil values that concern us. Recoil energy, which is equal to the ejecta energy. Recoil momentum, which is a function of energy and gun mass. Then we have recoil velocity - which is what we feel.

I know you asked Tuner, but if I may just add, the recoil is the result of the ejecta energy regardless of the launch platform's mechanism.

Regards
Peter