Hydraulic recoil spring?

[1911Tuner]

GLOOB, among other things, you forget to account for the broomstick.

Ah! The old broomstick. Yeah.

Back in 2007, I had a pistolsmith and custom knife maker from Monroe La bunk her for a couple weeks while he attended Montgomery County Community College to take an engraving course. Sure as rain, the talk turned to pistols. I'd written that rope/broomstick thing up on another board, but he couldn't wrap his head around it...until he actually did it for himself.

When he went home, he stopped by to visit with Jim Clark, Jr. and ran it by him. Jim was working on a gun at the time. He listened and didn't say much for about 2 minutes...laid his project down...blinked, and said: "I'll be damned. I never thought about it, but that's how it works. That's exactly how it works. I will be go to hell."

Those were his words...verbatim...as reported to me.

 

[1911Tuner]

As a matter of curiousity, if you do the math on this, using 485.8 grams for the weight of a GI spec 1911, bullet mass of 230 grains, in the complete lack of a recoil spring or any friction, you get the bullet only moving 3.26" by the time the slide recoils 1/10th of an inch.

When the math doesn't agree with the test results...go with the results and redo the equation.

You may have failed to include the barrel's weight/mass.

That's good information using high speed photography that JMB didn't have. I wonder how he cut things so close.

It's been said that Browning had the ability to see something with his mind's eye that he didn't have the math skills to prove on paper. He would often come out of the drawing room holding his thumb and forefinger apart and tell one of his engineers to "Make it exactly this big" and they'd measure the distance with a caliper, only asking: "How much tolerance"

It became known as: "Thinking like Mose."

 

[1911Tuner]

"Um, Gary, my name is not Willis. What I'm talking about is conservation of momentum.

There's one tiny detail that you haven't considered. While the bullet is in transit, before reaching the muzzle...it's more than simple conservation of momentum. While COM is always present any time that an object is moving...while the system is closed and operating under force...both ends are being accelerated by that force. Force forward and force backward. Once the bullet exits and all accelerating forces have vanished...all motion is conserved momentum...both bullet and slide, and neither one can accelerate to a higher velocity than they had at the peak of force and acceleration.

"Momentum will be conserved until an outside force is encountered."

Momentums are only equal in the absence of outside force, or in the presence of equal outside forces...and the outside forces in the gun aren't equal.

Read on.

Once the bullet has left the system, the only outside forces acting on it are air friction and gravity, while the slide is fighting both those things in addition to the recoil/action spring...the mainspring and hammer mass...and friction between the rails. The slide has met with outside forces that the bullet hasn't...from the git-go.

Your Gary and Willis on ice analogy assumed that all outside forces and momentums were equal. With the gun, those equal outside forces never exist...because the instant the slide moves, it has a different set of outside forces fighting it than the bullet.

And in the whole picture, you still refuse to acknowledge the frictional drag imposed by the bullet and its effect on the slide's acceleration.

Maybe if you factor it in, your equations would come closer to agreeing with the evidence presented in that photo.

 

[Peter M. Eick]

Tuner,

Could you please address how different power levels impact the dynamics of the 1911?

As an example, the 10mm in a 1911 is normally speced with a 22 lb spring. I put a flat bottom firing pin stop in mine and now run 18 lb springs. Reading this over, I could probably even go down to a 16 lb spring to reduce the beating up of the lower lugs as the slide slams closed. Is that correct assumption?

 

[1911Tuner]

Could you please address how different power levels impact the dynamics of the 1911?

Any increase in slide velocity will result in greater impact energy and momentum when it hits the frame, and any time higher stresses are imposed on a machine than it was designed to handle, there will be consequences, and anything that you can do to reduce or eliminate the impact stresses will extend the life of the gun.

No arguing that. Anything that is used enough will break or wear out eventually.

The question remains:

How much more impact...and for how long...can the abutments endure before they start to show deformation. And how much deformation can occur before it renders the slide or frame unserviceable? A few thousandths won't make a lot of difference.

So, the final question comes:

How long will it be until the frame and/or slide becomes unserviceable? To recap my own experience and the light flanging and slight setback that I've seen on a couple of the old, soft USGI frames...I dressed the flanging and continued to fire the gun for several thousand rounds without issue...only scrapping the frame when the rails became so worn that it wasn't worth the effort.

But even with the added impact imposed by full-throttle 10mm ammunition...it's not as critical as the other stresses on the gun.

The recoil or "locking" lugs in the slide and on the barrel are under tremendous shearing forces. The breechface is under much higher thrust forces than it was designed to accommodate.

A few thousandths of deformation/setback in the impact abutment is neither here nor there. A few thousandths in the lugs turns the slide and/or barrel into paperweights.

My contention is that a problem would show up in those areas long before any significant peening of the impact abutments became a concern if it ever happened at all. I have seen those those areas become a game-ending problem while the impact abutments showed no sign of peening or deformation.

 

[1911Tuner]

Peter...to illustrate what I'm talking about, study this picture.

I took this barrel out of an early Norinco...one of those that had poor barrel vertical engagement. The damage occurred in about 200 rounds. The root problem was that there was only about .028 inch of vertical lug engagement...or roughly 60% of the lug...but it shows what sort of shear forces are in play...even with the low-pressure .45 Auto cartridge.

Even with the relatively soft Norinco barrels, it takes a lot of force to deform steel like this. It also lends credence to my points concerning resistive forces imposed by the bullet on the barrel, and their effect on the slide's acceleration.

You can actually see the original lug face location, and the amount of deformation in the stair-step appearance that I called attention to earlier.

 

[1911Tuner]

Now, on the question of the 10MM and the 1911, I'll tell a little story.

A few years back, a friend of mine bought a 5-inch Ed Brown. He had a few minor feed/RTB issues and called Ed to see what the next step was. The question of ammunition naturally came up.

It was a 200-grain Hornady XTP loaded to 950-960 fps with Unique. I don't know the charge weight.

Ed's reaction was:

"Whoa, man! You're gonna break my gun!"

And full-throttle 10MM is a 200-grain bullet at an advertised 1250 fps.

You can draw your own conclusions.

 

[1911Tuner]

And finally...for the IMHO segment:

I think that the misunderstanding about the recoil spring's role came from Browning himself when he named it the "Re-action" spring in his patents.

People saw that word "reaction" and immediately thought of Newton's 3rd Law of action and reaction...and dubbed it the recoil spring.

And people have been arguing over it ever since.

 

[Peter M. Eick]

Thank you.

You might remember this picture so I can show that even the mighty 380 can peen metal with poor engagement of the lugs. I should point out that the barrel and slide actually would move back and forth and had motion prior to the peening of the metal. So poor fitting and soft metal caused this.



So basically, what I need to weigh is the lifespan of the barrel and slide verses the desire to run flat out 10mm loads? As long as I am not peening metal, I am just slowly beating the gun apart while if I tone it down, to 40 Short and Weak power levels I get more lifespan and if I tone it down to 45 power levels I will get even longer life span.

Sounds like a good reason to keep the full power 10mm loads in the G20 or Witness Hunter.

Thank you again for the discussion. I know we have talked about this before, but I wanted to see if you had any new insights.

PS: thanks for taking in the Husky's. My wife and I want one but we realize the implications and the need to allow them to run, so practicality has exceeded wants so far. I am pleased when I hear someone taking them in though.

 

[1911Tuner]

So basically, what I need to weight is the lifespan of the barrel and slide verses the desire to run flat out 10mm loads?

Pretty much. Like the old wisdom concerning K-Frame .357 revolvers goes: ".38 for fun and .357 for business." is good advice. Is there really a need for wide-open ammunition on the range, other than for a periodic reminder of how the business load feels?

I've seen that lug deformation in slides and barrels on the old, soft pistols. that's why the US Army ordered a dozen slides and 2 dozen barrels for every finished pistol they took. They understood where the real stresses were.

 

[Jim Watson]

The question is whether a Delta Elite will handle the heavier 10mm loads at all. The boutique brands seem to be most often involved. Underwood says:

"10mm Auto

Cannot be used in Colt Delta Elite or any other firearms with rampless barrel due to complete lack of case support.

Safe for use in all 10mm firearms with a ramped feed barrel.
(Examples: Glock, EAA Witness)"



There are pictures here and elsewhere of DEs with blown caseheads due to the barrel ramp being wallowed out like a .45 wad gun.

 

[1911Tuner]

The question is whether a Delta Elite will handle the heavier 10mm loads at all. The boutique brands seem to be most often involved. Underwood says:

After somewhat limited observation with the DE, I have a few thoughts on those points, Jim.

As long as the headspace is good, there's little danger of a case head blowout, even with full-throttle ammo. I believe the problems start as the lugs start to deform, with the attendant increase in headspace in the kaboom direction as the case backs up progressively farther in the chamber until it reaches a point of lack of support just forward of the chamber in the thin part of the brass.

The basic problem with the 1911 is the small radial lugs that may or may not all be taking the brunt of the recoil forces. The way to forestall the deformation is to have a barrel fitted with equalized lugs, which is only rarely the case with a factory installation...and even with that ideal setup, there still isn't a lot of surface area to handle the recoil stresses of the Big 10.

And even equalizing lug engagement doesn't help at all with the tensile stresses and thrust on the breechface. That's a whole 'nother beast.

The lugs are the weak spot in the 1911. In that respect, it's a fine pistol, but it's not an exceptionally strong pistol. Much better with modern steels, but still lacking in the brute strength to needed handle what the 10 can dish out.

It's probably time to throw in the towel concerning a 1911-pattern 10MM unless the owner accepts loading to its full potential on a need-only basis and downloading for recreational use...the same as sensible people do with K-Frame .357 Smiths. That's my 2% of a buck, anyway.

 

[barnbwt]

What we need is some clever way to get lugs on the sides or bottom of the slide to get the additional contact area we need for the barn-burners --then we'd be in business

I also found that contact area is the hardest thing to design around when it came to the various gun designs I've sketched out and run numbers for. There is a somewhat exponential growth that occurs much higher than service pistol rounds, where the platform jumps to rifle-sized configurations and their much more efficient use of space for locking lugs (namely rotating bolts)

Something interesting just occurred to me as far as damping instead of mass or springs to slow the speed of the slide. I own an R51 (and it works fine, so shut up ) and the way the action works has, I think, a substantial damping effect on the slide's velocity. The intial blowback starts the slide moving, but then it must drag up the locking block once pressures drop, then accelerate it backward (and then depress the stiff disconnector not once, but three times ) before reversing course. It's not hydraulic damping, but the effect is the same, in that the gun has an exceedingly light return spring, yet suffers nothing but cosmetic peening of the frame abutment that stops the slide (so far). So if the 1911 is designed/configured in such a way that excessive "clank" is applied to the slide stops, a dash-pot damper would actually improve felt recoil and could possibly reduce the spring weight needed.

TCB

 

[barnbwt]

"This forward drag has been measured by the man who posted those pictures. It took 103 pounds of force to start the bullet into the rifling, and 93 pounds of steady force to get it to the muzzle.

This represents the strongest resistive/delaying force acting on the slide in the whole system. It explains why a locked breech pistol can be safely fired without a spring and it explains why the barrel can't unlock with a heavy-for-the-caliber bullet and high pressure can't cause the barrel to unlock early."

That also explains why my R51 shot just a teensy bit smoother with its narrow/short and incredibly rough & ridged chamber (made with a dull endmill or something, so no leade ) before a friend of mine reamed it out to spec. The brass was losing a good .001" of material as it was extracted from the sand-papery chamber before, which actually soaked up enough recoil force to halve the ejection distance. The brass comes out burnished all pretty like, now

TCB

 

[thefish]

Wow, all I can say is Wow.
That is way more information I thought I would ever know from what I thought was a simple question.
Thanks so much for the in depth discussion. As usual, you guys have gone above any beyond. Way beyond!
That new CCP may be worth looking into.
Thanks again!

 

[JRH6856]

That also explains why my R51 shot just a teensy bit smoother with its narrow/short and incredibly rough & ridged chamber

Maybe. The R51 barrel is fixed to the frame so the bullet is pulling the gun forward in your hand while the breechblock and slide are moving backward and trying to pull the case out of the chamber. Might be a further contributor to low muzzle flip.

Fish, you never know what a simple question might produce around here.

 

[barnbwt]

"Fish, you never know what a simple question might produce around here."
My quip about angels on pin-heads may be more true than we'd think; the 1911's probably received more scrutiny (due and undue) in the last century than nearly any particular mechanical device (small block Chevy's, maybe). So I'll bet there's 'controversy' surrounding even something as random/pointless as...I dunno... sear pivot pin dynamics, or some nonsense

"Maybe. The R51 barrel is fixed to the frame so the bullet is pulling the gun forward in your hand while the breechblock and slide are moving backward and trying to pull the case out of the chamber. Might be a further contributor to low muzzle flip."
The friction of a stuck case would act on the action very similarly to a damped guide rod (and it had better have been unintentional in the case of the R51 )

TCB

 

[barnbwt]

"This forward drag has been measured by the man who posted those pictures. It took 103 pounds of force to start the bullet into the rifling, and 93 pounds of steady force to get it to the muzzle.

This represents the strongest resistive/delaying force acting on the slide in the whole system. It explains why a locked breech pistol can be safely fired without a spring and it explains why the barrel can't unlock with a heavy-for-the-caliber bullet and high pressure can't cause the barrel to unlock early."

Ok, something didn't sit right with me on this, and I think I have it, now. It does not matter how much load is borne by the rifling, because it is rolled into the bullet momentum regardless. Were the slide frictionless, the bullet would simply go faster, due to increased momentum transfer efficiency from powder to bullet. So it really doesn't 'delay' anything more than a down-loaded cartridge would. The closed system is the barrel and slide while linked, which are the same mass. The slide may pull the barrel along for the ride, but neither moves relative to the other, so they might as well be welded.

Maybe I missed the point of the "Broomstick" exercise, because the muzzle momentum of the bullet does still has to equal all the work that was done on the firearm (which that early in the cycle is likely solely upon the slide, barrel, and hammer). If we were computing momentum from the powder chemical energy or something, barrel friction would skew the figures, as would a whole host of other efficiency factors, which is why muzzle momentum is the most useful figure to measure for these things. Because the tension is long gone before the slide/barrel move relative to one another, how could it possibly effect the gun's operation? It's done no work.

TCB

 

[1911Tuner]

Too complicated, barn. It's a lot simpler than that. That's why I use the broomstick analogy. Anyone can do it and see what the effect is.

I'll recap it at the end, but for now...

If slide and barrel mass is all that's needed to effect the delay needed...explain the Luger.

Then take a look at our favorite blowback punching bag...the High Point. Specifically, the .45 caliber High Point.

The HP's slide weighs as much as an unloaded LW Commander, and the spring in that thing is a beast. I'd estimate that at full slide travel, it'll hit about 38-40 pounds. Doing an overhand opposing push hand-cycle...I could barely manage to engage the slidestop and lock the slide back...and I'm not weak.

So, why does the HP have such a massive slide and unbelievable spring load for the same cartridge?

Now, compare the 9mm version to the Luger. The slide is the same size/weight/mass as the one on the .45 and while the spring is a lot easier to manage...it's still pretty stout.

Again...why all that slide mass and spring load for the same cartridge?

The unlocked breech/blowback delays breech opening with slide mass and/or spring load...but until the High Point came along and gave it a whirl...nobody offered and a straight blowback pistol in either of those calibers specifically because the slide would have to be so massive and the spring so strong, it wasn't considered practical or marketable.

Straight blowback was limited to cartridges like the .380 and the .32 and the .25 and the .22 Rimfire because those cartridges were the only ones that could be used and keep the pistol's bulk and weight at a reasonable level.

On to the "broomstick" demonstration.

Grip it in front of you with both hands. Start pulling in opposite directions with gradually increasing force, then >slightly< loosen your grip with one hand...just enough to let it slip.

The instant that the stick slips and starts to move...your hand starts to move in the opposite direction. The stick resists your hand and your hand resists the stick.

Because...whatever resistance your hand offers to the stick, the stick offers to your hand. In the gun...whatever resistance the barrel offers to the bullet, the bullet offers to the barrel...and whatever resists the barrel's backward movement, resists the slide.

That's why GLOOB's insistence that a heavy bullet will let the barrel unlock early won't fly. A heavier bullet is a longer bullet and a longer bullet means more surface area in contact with the barrel and more surface area with the barrel means a higher friction load and a higher friction load means more resistance....and more resistance means slower slide acceleration.

It also explains why in a longslide 1911, the tenth-inch slide travel and the tenth-inch bullet distance from the muzzle is still there. Go find a high-speed video and see for yourself. Because...as long as the bullet is in the barrel it's resisting the slide.

Whatever you do to one end of a closed system, you do to the other end.

During one of my workshops, I had a bright young fella here who had a fresh 4-year mechanical engineering degree under his belt. When we got to the bullet-induced delaying effect on the slide, and everybody else's brow furrowed as they tried to wrap their heads around it...he grinned and nodded. He saw it. When one guy started talking about much the same things that you just did...he told him that he couldn't simply ignore a force that he didn't understand. It's there. It has an effect.

Finally...if you understand the principles of explosive movement, you can hand-cycle a 1911 slide as fast as it moves when it fires...or maybe a bit faster.

But...if you slip a bullet into the chamber and tether the other end to a wall...you can't pull the barrel off the bullet at the same rate that the barrel moves when the slide pulls it when the gun fires. Try it. You can't do it. You can't even do it with a lead bullet.

Keep thinking about it, and remember that Newton 3 is in play any time a force is in play...whether the object is being pushed or pulled. When you push on an object, you immediately get pushed away from that object. When you pull on an object, you immediately get pulled toward that object.

When this first occurred to me about 20 years ago, I put the question to a couple of sharp career engineers. They both said:

"Well, sure. If there's a resistance in one direction, there's an equal resistance in the other direction. There must be. Force forward is force backward."

Maybe it would help to think of it in the same way as inertia...like a heavy weight that you have to lift. It doesn't have to "do work" in order to offer resistance to acceleration. It just has to be there.

GLOOB...I deleted your snarky post. We're not gonna do snark. It wastes bandwidth and adds nothing to the discussion. If you can't get that, I'll keep deleting.

 

[GLOOB]

Yeah, I'm sorry. I deleted it myself before you did. But I did leave the comment that I deleted a snarky comment. After you deleted it, you didn't have to point out that you deleted it, and that it was snarky. Now, there's still a record that I made a snarky comment, and that you deleted it. So, well, now I have to say I'm sorry. So, I'm sorry. And for the record, it really wasn't that bad, IMO.

 

[GLOOB]

.

So, why does the HP have such a massive slide and unbelievable spring load for the same cartridge?

Is it because if the breech were to open even 1/10th of an inch by the time the bullet exited the muzzle, the case head would blow apart?

Finally...if you understand the principles of explosive movement, you can hand-cycle a 1911 slide as fast as it moves when it fires...or maybe a bit faster.

But...if you slip a bullet into the chamber and tether the other end to a wall...you can't pull the barrel off the bullet at the same rate that the barrel moves when the slide pulls it when the gun fires. Try it. You can't do it. You can't even do it with a lead bullet.

Perhaps you cannot. That energy that goes into overcoming friction turns into heat, does it not? It heats up the bullet and the barrel? And also it swages/deforms the bullet? Some of the energy of the cartridge is used up in doing these things? And some of what's left of that energy is what sends the bullet at 900fps - and the slide in the other direction, right? So it is just THIS part of the cartridge's energy that is all you need to replicate when you rack the slide like a ninja, is it not?

So let's ask this question. If you understand the principles of explosive movement, can you throw a 230 grain bullet 900fps? I do not think this is humanly possible. But if it is, as you say it is, possible to rack a slide as fast as what happens when a gun fires, is it because the slide weigh 30 times as much as the bullet and only moves one thirtieth the speed? So maybe, like, the same way you can punch someone with way more momentum and about as much kinetic energy as what is carried by a 45ACP bullet, you can rack a slide that fast? But you can't match the velocity of a bullet?

(And fun fact: you can punch someone with way more momentum AND way more kinetic energy that what the slide carries. The slide has the same initial momentum as the bullet, but by virtue of kinetic energy being a function of velocity squared, the bullet ends up getting a way bigger share of kinetic energy than does the slide.)

 

[1911Tuner]

But you can't match the velocity of a bullet?

Nope...but you can't pull the barrel off a tethered bullet at the same rate as it's pulled by the slide when the gun fires, either. We're talking about slide acceleration now. Let's try to keep it apples to apples.

Let's go back to the High Point, et al.

Explain the High Point's massive slide and that godawful
spring. Do you think that High Point's engineers used a 26-ounce slide and a 40-pound spring just for giggles?

Why not just use a 17 or 18-ounce slide on the High Point with a reasonable spring and make the barrel about > < that much shorter instead of marketing the klunky, top-heavy beast that it is?

Then...explain the Luger's low-mass breechbolt.

If the 1911's slide/barrel mass is all that's needed for the delay...why didn't Browning design it as a blowback and make the barrel a 10th inch shorter? It woulda been a helluva lot simpler and easier.

Or do you really believe that tying the barrel to the slide for 1/10th inch of travel is all that's needed to give the bullet time to escape?

Think about these things carefully.

 

[GLOOB]

Oh, facepalm! I can see what your point is, now, about the broomstick. You are saying that the friction of the bullet makes the slide on a High Point go back faster. Since it's straight blowback, it's like an OOB ignition. The slide has to counteract the force of the bullet being swaged, as well as the friction of the bullet going down the barrel, in addition to opposing the momentum of the bullet! Perfect sense. This whole time I thought you were using the broomstick to explain a locked breech system.

So in a High Point, the slide will possibly move back just as far or even farther, compared to a 1911, at the point in time when the bullet is clearing the muzzle, despite the fact that the slide and recoil spring are heavier, basically?

But I still don't quite follow the reasoning how a locked breech gun will work with any weight bullet. That part still don't jive. In the locked breech setup, the friction is completely cancelled out. The bullet swaging and friction does not translate into momentum, because the breech IS locked. The only place that an increase in friction makes a difference, I thought we had agreed, was the force it places on the locking lugs (and more energy turned into heat). So a longer bullet has more friction, but that friction does not affect the momentum of the slide/barrel. The extra mass of the longer bullet, however, does.

 

[1911Tuner]

So when I asked this question about the Hi-Point: "Is it because if the breech were to open even 1/10th of an inch by the time the bullet exited the muzzle, the case head would blow apart?"
Your answer is no? The case would not bubble out and/or rupture, in your opinion?

Well, of course it would. That's why the High Point has a massive slide and that OMG! spring.

Those things aren't needed, nor are they present in a locked breech pistol...because there's something else working to delay it...and it's more than a 10th inch of barrel.

Now...explain the Luger and compare it to the 9mm High Point.

 

[1911Tuner]

Think hard, and consider one more piece of evidence on this video.

If that had been a straight blowback with the same slide mass and spring...it would have wrecked his thumb and wrist.

But it didn't. He was able to keep the slide from budging without even straining.

http://www.youtube.com/watch?v=Gw8sbb8eDjg