200 vs. 230gr .45 ACP's

[74A95]

If folks want to see muzzle rise in a semi-auto before the slide stops at the rear, it's right here in this video:

https://www.youtube.com/watch?v=ULysvxSYfoU

[polyphemus]

Again,slide and barrel travel rearward together as soon as the bullet starts moving for about 1/8"and then disengage.Not enough to cause any rise.
And Browning did mean that the slide is delayed during that time in the same sense that delayed blowback is understood,it is moving and gaining momentum but this motion is somewhat curtailed by counter forces. After that the slide continues on but momentum decreases since force is no longer present.Short recoil operated arms do not function like revolvers or rifles.

[T. O'Heir]

Easiest thing to do is aim higher. Like ms6852 says, it may be a dead on hold or it may not be.
"...Does not make sense that..." Does. It's a different load with a different bullet. It'll have a different POI.

[44 AMP]

Of course I think otherwise neither a revolver nor a rifle is a semi auto pistoand I don't shoot either,so please tell us, what force exactly makes a muzzle rise

We did. Repeatedly.

Again,slide and barrel travel rearward together as soon as the bullet starts moving for about 1/8"and then disengage.

This is a fact.

Not enough to cause any rise.

This is your opinion, not a fact.

If you are going to hold to your belief that it is slide movement that causes muzzle rise, then please explain why firearms that do not have a slide have muzzle rise, the same as those with a slide do.

[Metal god]

If you are going to hold to your belief that it is slide movement that causes muzzle rise, then please explain why firearms that do not have a slide have muzzle rise, the same as those with a slide do.

Seems like a reasonable question and one I'd like to know the answer to . However maybe we need to go back farther into the thought process to understand where he is coming from .

Poly

Do you believe the mechanical workings of the firearm is the only factor causing recoil ?

I feel we are talking past each other and you are thinking we don't believe the slide causes recoil , IMO it does and quite a bit . We believe there is some movement of the firearm upon ignition , IMO there is but not much in comparison to the over all recoil of the firearm .

Lets try this as a way of thinking about it . Newtons law and the equal and opposite reaction aspects . If it takes 1lb of force to move something forward there is 1lb of force being applied to the rear as well ??? OK lets "assume" this is true for a second . If a bullet has a muzzle energy of 400 foot lbs at the muzzle surely when it starts moving at ignition of the powder is has at least some energy in foot lbs being applied . Even if it's only 1 foot lb pushing the bullet forward It's still a force pushing the bullet in one direction . For this to happen there must be an "equal" and "opposite" reaction in the opposite direction which means there "must" be a force of the same amount pushing rearward on the firearm . That force will move the firearm when held in anyone's hand . Do you think you could hold the firearm perfectly still if someone tapped the muzzle rearward with a force of 1 foot pound ? No you could not because just the sponginess of the skin and muscles in your palm will allow anything to move a little regardless of how hard the force is applied or how hard/tight you hold the grip . Just clinch your fist real tight and push on the skin around your palm with the other hand to see how soft your grip really is .

[polyphemus]

If you are going to hold to your belief that it is slide movement that causes muzzle rise, then please explain why firearms that do not have a slide have muzzle rise, the same as those with a slide do.

ok, at the risk of being called a troll...

A revolver would do then,now your pivot point diagram applies this is because most of the the recoil force is transferred directly to the shooter.A slide's mass and other relevant factors like friction and springs contribute to dissipate the energy generated at ignition,the remaining slide momentum causes the muzzle flip at the end of the rearward travel.

[polyphemus]

Do you believe the mechanical workings of the firearm is the only factor causing recoil ?

I am convinced that an equal force as that which sends the bullet flying out sends the slide back in recoil.
I think that the length of time a bullet spends in the barrel can only be relevant for trajectory purposes if the comparison is made between two or more bullets of different weight at the same velocity.
We're not talking past each other I'm simply being asked to prove something that seems logical to me but I lack the instruments to measure.If .120" of slide
travel at the beginning of recoil causes the muzzle to rise then so be it.

[USSR]

I am convinced...,
I think..., seems logical to me...

No room for scientific facts here. You are definitely "winging it", but carry on.

Don

[JohnKSa]

Ok, lots of confusion here.

I did some experiments awhile back comparing sightline and bore line for revolvers vs. Browning type semi-auto pistols and found that they are quite different.

Revolvers are set up to compensate for significant muzzle rise between the time that the trigger is pulled and the bullet exits the bore. The same would be true of any fully locked breech action like a gas operated action (such as the Desert Eagle) or any manual repeater as long as the boreline is above the point of resistance caused by the shooter's grip.

But linkless Browning type semi-auto pistols are set up differently. The borelines and the sightlines are almost perfectly aligned. In other words, they are not set up to compensate for any significant muzzle rise between the time that the trigger is pulled and the bullet exits the bore.

Recoil DEFINITELY begins when the bullet starts moving. There is no room for debate on that point.

It's important to understand that muzzle rise and recoil are two different things.

Recoil is an unavoidable consequence of bullet movement.

Muzzle rise sometimes results from recoil depending on the circumstances. And it may not happen immediately.

Recoil does not always cause muzzle rise. If the recoil vector is straight back into the point of resistance, the recoil motion will be straight back. If the recoil vector is above the point of the resistance, the recoil will cause muzzle rise. That's the first complication.

In addition, even when recoil does cause muzzle rise, it does not always have to cause significant muzzle rise immediately. In the case of the linkless Browning type semi-auto pistols, the recoil initially causes the slide and barrel to move backwards, resisted only by the force of the recoil spring. That remains true, by design, until the bullet exits the bore and the barrel and slide unlock. Because the recoil spring presents a relatively small resisting force, the muzzle rise during this phase of recoil is minimal--the slide and barrel move pretty much straight back with no significant force being transferred to the frame of the gun. We can see that this is true by looking at the sightline vs. boreline for this type of pistol and noting that there is no attempt to compensate for muzzle rise.

The muzzle does rise a very little bit due to the loose coupling of the slide/barrel to the frame via the recoil spring, but not very much at all--certainly not nearly as much as would be seen in a revolver, or in a gas operated pistol like the DE. This post contains a very thorough analysis of just how much the muzzle of a Browning type action might rise while the bullet is in the bore.

Once the slide and barrel travel backwards far enough to reach the unlocking point, the barrel stops against the frame (or against something that bears against the frame) and that provides the first direct coupling of the recoil energy to the frame of the gun. At that point muzzle rise begins to really show up. However, it's important to remember, that, by design, the linkless Browning type semi-autos do not unlock until the bullet has left the bore. So the really significant part of muzzle rise happens after the bullet is gone.

Browning type pistols with links that begin tilting the barrel immediately when recoil starts are sort of a different category and I haven't done measurements on them.

[Metal god]

.If .120" of slide
travel at the beginning of recoil causes the muzzle to rise then so be it.

See we are talking past each other because my belief is that no parts of the gun are moving the first maybe 1/2" of bullet travel . Nothing , not the slide nor the barrel have moved when the bullet first starts moving . You need to remember there needs to be enough pressure built up to force the slide back or to unlock/disengage the barrel from the slide . While those pressures are building the bullet has already stated to move . If the bullet is moving forward there must be a force pushing rearward equal to the force pushing the bullet forward that first 1/8 , 1/4 , 1/2" . What ever that movement may be there is a force being applied in both directions before the pressure builds enough to start operating the external workings of the firearm .

hmm as I wrote that a question accrued to me . If the pressures of the gas expanding are equal in all directions . Do they all cancel each other out as a force in any one direction ? If the gases are pushing equally rearward as they are forward on the bullet , does that make a neutral force being applied ?

[JohnKSa]

See we are talking past each other because my belief is that no parts of the gun are moving the first maybe 1/2" of bullet travel .

That belief is contradicted by the basic principles of physics.

Recoil motion is caused by conservation of momentum which is a product of motion and mass. Once you have bullet motion, you have momentum and you also have recoil.

Recoil motion can be very small and slow if the momentum creating it is small relative to the recoiling mass, but it will start as soon as there is any momentum to generate it.

You need to remember there needs to be enough pressure built up to force the slide back or to unlock/disengage the barrel from the slide .

Recoil moves the slide back in a "recoil operated" action. Pressure can not unlock/disengage the barrel from the slide in a Browning style locked breech, recoil operated action. Only the rearward motion of the slide and barrel that is caused by recoil can cause the unlocking process to occur.

[Metal god]

Recoil moves the slide back in a "recoil operated" action. And pressure can not unlock/disengage the barrel from the slide. Only the rearward motion of the slide and barrel that is caused by recoil can cause the unlocking process.

Exactly , so if the bullet moves a full 4 or 5" before exiting the barrel and the Browning design does not allow the slide or barrel to move/unlock until the bullet has left the barrel or moved that 4 or 5 inches

the linkless Browning type semi-autos do not unlock until the bullet has left the bore.

Which I do not believe because once the bullet leaves the barrel the pressure drops to zero . If the bullet is gone and there is no pressure left in the bore what is forcing the slide back ?

. There must be a force being applied to the bullet to propel it that 4 or 5 inches . What happens to that equal and opposite reaction energy in that 4 or 5 inches of bullet travel if none of the guns mechanical parts have started moving yet ?

[JohnKSa]

Exactly , so if the bullet moves a full 4 or 5" before exiting the barrel and the Browning design does not allow the slide or barrel to move/unlock until the bullet has left the barrel or moved that 4 or 5 inches

The action CLEARLY moves before the slide/barrel unlock. There are ultra-slow motion videos online demonstrating that this is true.

Here's one. It shows the muzzle of a 1911 pistol starting at 2:13 in the video. The slide and barrel are definitely moving before the bullet exits.
https://youtu.be/kq-xcqs5NIk?t=2m13s

That is comforting because physics tells us that the slide/barrel combo begins moving the instant that the bullet begins moving.

The slide and barrel do not unlock until they have moved far enough to activate the unlocking mechanism. That, by design, happens after the bullet has left the bore.

So recoil motion begins when the bullet begins moving--unlocking happens after recoil motion has moved the barrel and slide back far enough to unlock the action--after the bullet has exited the muzzle.

Which I do not believe because once the bullet leaves the barrel the pressure drops to zero .

Which you do not believe because you refuse to accept the scientific principles of conservation of momentum and the fact that a recoil-operated action is actually recoil-operated. The motion of the slide/barrel which unlocks the gun is due to recoil. Pressure does not, can not, unlock the slide/barrel.

Once the slide and barrel are in motion, they will continue moving until some force stops them. So they continue moving after the bullet leaves the bore due to the "boot" they got from the recoil force.

There must be a force being applied to the bullet to propel it that 4 or 5 inches .

Of course there is. And the result of that force being applied is bullet motion which generates momentum and results in recoil motion due to conservation of momentum.

What happens to that equal and opposite reaction energy in that 4 or 5 inches of bullet travel if none of the guns mechanical parts have started moving yet ?

They have most certainly started moving. They just haven't moved far enough to unlock the action until after the bullet exits the bore.

[Metal god]

ok now we're talking past each other or at least I am

[JohnKSa]

Watch the video. The slide and barrel definitely move before the bullet exits.

[Metal god]

They have most certainly started moving. They just haven't moved far enough to unlock the action until after the bullet exits the bore.

There you go the gun is moving before the bullet leaves the bore . How can that not effect POA to POI ? It may be small but it's does , correct ? How long the bullet is in the barrel should have an effect as well , correct ? That's all that's been being said or at least that's how I've been comprehending what "are" side of this debate has been saying .

[Metal god]

Watch the video. The slide and barrel definitely move before the bullet exits.

They have most certainly started moving. They just haven't moved far enough to unlock the action until after the bullet exits the bore.

These seem like contradictory statements . Are you talking about the shutter of the gun as it absorbs the combustion of the powder as the first movements of the gun ?

I think I'm misunderstanding what movement exactly you are talking about before the slides starts to move and unlocks the barrel ?

[JohnKSa]

There you go the gun is moving before the bullet leaves the bore . How can that not effect POA to POI ? It may be small but it's does , correct ?

It will effect POI IF the recoil vector is not directly centered on the point of resistance during the time that the bullet is in the bore.

The key here is the statement I made in my first post. It's important to understand that muzzle rise and recoil are two different things.

In a pistol, unless the recoiling mass can recoil completely freely (no coupling at all between the slide/barrel combo and any point of resistance, and the slide/barrel balanced perfectly around the bore) there will be some POI effect since the recoil will push the bore offline and change the POI.

In a linkless recoil-operated design, there is only the recoil spring coupling the slide/barrel to the frame while the bullet is in the bore and that is a weak coupling effect. So there is SOME POI effect, but it is very small. It would likely have an effect smaller than a tenth of an inch at 25 yards based on the analysis in the link I provided above.

The simple answer is: "Yes, recoil does affect POI in any real world gun." HOWEVER, a more complete answer is that in some designs the effect is so small that it is insignificant and should be ignored.

I think I'm misunderstanding what movement exactly you are talking about before the slides starts to move and unlocks the barrel ?

The slide moves for awhile before it unlocks the barrel. It is impossible to get an accurate picture of what's going on without understanding that slide motion doesn't INSTANTLY result in unlocking.

The slide has to move between a tenth and 2 tenths of an inch before unlocking happens.

Pause the video at 2:13 and put a sticky note on the screen where the muzzle is. Now run the video and stop it when the bullet just starts to poke out of the bore--at 2:25. Notice how far the slide/barrel has moved. By design, when the bullet exits, the slide/barrel haven't unlocked. But you can certainly see that they have moved.

[polyphemus]

HOWEVER, a more complete answer is that in some designs the effect is so small that it is insignificant and should be ignored

.
Thank you,I've trying without luck to find something in your posts that I disagree with.

[44 AMP]

A revolver would do then,now your pivot point diagram applies this is because most of the the recoil force is transferred directly to the shooter.A slide's mass and other relevant factors like friction and springs contribute to dissipate the energy generated at ignition,the remaining slide momentum causes the muzzle flip at the end of the rearward travel.

If I am understanding you correctly, you are stating that the energy of recoil is "dissipated" (completely used up and gone) before the slide reaches the end of its travel and therefore recoil is not a factor in muzzle flip.

I do not believe this to be the case. I am not disputing the mass of the slide moving and stopping contributes, I am disputing that it is the cause.

And, here's why,
Momentum

JohnKSa hit on this, let me try and explain it a different way.

Recoil starts when the bullet starts moving. The "push" continues until the bullet leaves the barrel and the pressure drops.
Between the time the bullet starts moving and the time the pressure drops, parts of the gun move. The locked together barrel and slide move back from the recoil, relative to the frame.
When the barrel stops, transferring the force of its movement to the frame, that force rotates the pistol in your grip. Not a lot, but some, and very shortly after that, the slide stops, transferring that energy to the frame in your hands, ADDING to the rotational movement and further raising the muzzles, but the bullet is by now long gone.

The effect of recoil energy transmitted to the frame is greater in "standing breech" guns but it is there in Browning tilt barrel guns as well, it just isn't spread out over time.

And we are talking about very, very small increments of time. Much too small to be discernable to human senses. And I think time here, is the key, we are talking about why heavier bullets strike higher on the target (from a pistol at 25yds) At that distance you would think that the faster bullet (the lighter one) should hit HIGHER on the target, because since it gets to the target sooner, it has less time for gravity to pull it down.

But that isn't what happens. Even at short pistol ranges, there is an arc to the bullet flight, one well known and guns are designed to allow for this. The barrel is actually pointed very slightly "up" in relation to the line of sight. This is because gravity starts pulling down the instant the bullet leaves the barrel, so, in effect we "lob" bullets at our targets. Every one, no matter what it is or what its fired from, the ballistic arc is a constant factor.

Now, given this, why does the faster lighter bullet still strike lower on the target is this instance? Because the barrel also moving "up" due to recoil, and the lighter bullet begins its ballistic arc at a different point of barrel rise than the heavier bullet. If you have a different idea to explain why lighter bullets hit lower, I'm listening...

Recoil keeps "pushing" after the bullet is gone, due to momentum. To illustrate, find a heavy door. A safe door is a good example. SLAP the door, it barely moves. Inertia. PUSH the door with force equal to the slap, and the door moves as the inertia is overcome, and will keep moving (again, inertia) after you stop pushing.

Recoil pushes long enough (the time the bullet is in the barrel) to get the whole gun moving, and the inertia of the gun's mass keeps it moving after the bullet is gone. So, through inertia, the momentum of the moving mass of the firearm, recoil is still "pushing" though no additional force is applied after the bullet is gone.

[JohnKSa]

If I am understanding you correctly, you are stating that the energy of recoil is "dissipated" (completely used up and gone) before the slide reaches the end of its travel and therefore recoil is not a factor in muzzle flip.

Recoil does result in significant muzzle flip when the slide/barrel impact against the frame. However, this happens AFTER the bullet has left the barrel in a recoil-operated, locked breech design.

So you do get muzzle flip as a result of recoil, but you don't get significant POI change as a result. That's because the significant muzzle flip doesn't really happen until after the bullet is gone.

The RECOIL motion starts immediately--simultaneous to the start of the bullet motion. But initially, all the recoil motion is nearly directly straight back without significant muzzle flip because the slide/barrel combo can move almost directly straight back until the unlocking action takes place. By the time the slide/barrel hit the frame and cause significant muzzle flip, the bullet is gone.

[Metal god]

Sorry had to leave to do some X-mas shopping but I'm back ( happy joy )

The RECOIL motion starts immediately--simultaneous to the start of the bullet motion. But initially, all the recoil motion is nearly directly straight back without significant muzzle flip because the slide/barrel combo can move almost directly straight back until the unlocking action takes place.

This is assuming there is nothing resisting the slide and barrel when it starts to move . All my pistols have a pretty heavy spring keeping them closed or the slide fully forward on the frame.

Is this the design we are talking about ?
Browning highpower
https://www.youtube.com/watch?v=JeIyN1Eke-U

Looks to me that the rod and spring are pushing against the frame when fired or even manually operated . although different my XD 45 seems to do the same thing . So how does the slide move even a fraction of an inch and that rod and spring not put direct rearward force against the frame ? My XD is the same way , The rod sits fully on the front of the slide but is only on half of the barrel/chamber area . The other half of the rear end of the rod is pressing/forced against a section of the frame . The slide can not move with out putting force on the frame . Further more that force is well below the center axis of the bore . So how is the slide moving with out effecting the frame ?

I'm no math batition so help me out here on this part . How much would a muzzle need to move in any direction to cause a 1" POA movement on target at 25yds . I'd think that movement would be pretty small , a guess would be 0.050" . Would anyone consider that significant muzzle movement when it comes to the over all complete recoil movement of a pistol when fired ?

[JohnKSa]

This is assuming there is nothing resisting the slide and barrel when it starts to move . All my pistols have a pretty heavy spring keeping them closed or the slide fully forward on the frame.

Correct. And the coupling due to the spring does cause some muzzle rise, but very little. In my first post I provided a link to a very thorough analysis of how much POI difference would likely result from the spring force resistance. Going from 230gr to 185gr changes the POI at 25 yards by about 0.12".

So it does make a difference, just a very small difference--one so small it can be ignored for most practical purposes.

With revolvers, however, things are much different. Because the barrel is fixed to the frame and the point of resistance from the shooter's grip is well below the bore, there is considerable muzzle rise before the bullet leaves the bore.

Look at this picture of a revolver.



Notice that when the sights are level, the bore is obviously pointing downwards. To hit something level with the sights obviously requires the muzzle to rise a considerable amount between the time that the trigger is pulled and the bullet exits the bore.

One can do a similar comparison with autopistols of the type being discussed here and see that there is nowhere near as much compensation. In fact, when I did my analysis of autopistol borelines vs. sightlines I actually found that some autopistol bores were pointing upwards with respect to the sightline--a significant difference from what is seen in revolvers.

[USSR]

How much would a muzzle need to move in any direction to cause a 1" POA movement on target at 25yds .

"How many angels can dance on the head of a pin"? The fact is, the discharge of a round in a firearm that is held (supported) below the barrel results in the muzzle rising during said discharge and influences the POI of the bullet to some degree. In the case of the OP, he is finding that a lighter bullet (which is producing less recoil and may or may not be traveling faster) is being influenced less by muzzle rise during discharge than a heavier bullet. The fact that we are arguing about something that has been known by shooters for a hundred years or more is ridiculous.

Don

[JohnKSa]

In the case of the OP, he is finding that a lighter bullet (which is producing less recoil and may or may not be traveling faster) is being influenced less by muzzle rise during discharge than a heavier bullet.

That's not really what the OP says. He's asking how to adjust the POI by changing ammunition, not stating that he's seeing a difference in POI from changing ammo.