Grand Power Xcaliber Vs Tanfo Stock 2

[Wesquire]

The dwell you see in slo mo videos with the slide aft isn't momentum transfer happening. Thats the slide accelerating from a stand still. The recoil part is well over at that point.

It is both. The acceleration doesn't happen until after the momentum has been transferred though.

[busdriver02]

How much time it takes for the slide and frame to have the same velocity (momentum transfer as we've been calling it) is a function of materials. The entire rearward cycle of the slide takes place in about 10ms, .01 seconds. That includes the time of collision. The only faster or slower to that is elastic and/or plastic deformation of the frame and/or slide. And it ain't much.

Feel free to not believe me, I've been wrong a time or two in my life, and the human body is capable of perceiving some amazingly small details.

But I'm pretty sure I'm right.

Edited November 17, 2015 by busdriver02

[Wesquire]

I dont know much about the design of pistols, I am just getting in to the sport myself but I know a little about engineering and when I saw the design and read it accounted for less recoil I thought it was based on the simple mechanism on the barrel to turn linear movement in to rotational movement.

Some of the forces that would act to push the pistol back are also rotating the barrel which hits a hard stop.

How much is absorbed I dont know but it must be something.

By that thinking, they could just make the barrel really hard to rotate and take off a ton of the recoil. It doesn't work like that. It takes very little force for the barrel to rotate. Think about it, the barrel is rotating when you rack the slide. Does it take a lot of effort to rack the slide? No, and most of that is fighting friction and the recoil spring. The rotation is nothing. It is a red herring.

[Wesquire]

How much time it takes for the slide and frame to have the same velocity (momentum transfer as we've been calling it) is a function of materials. The entire rearward cycle of the slide takes place in about 10ms, .01 seconds. That includes the time of collision. The only faster or slower to that is elastic and/or plastic deformation of the frame and/or slide. And it ain't much.

Feel free to not believe me, I've been wrong a time or two in my life, and the human body is capable of perceiving some amazingly small details.

But I'm pretty sure I'm right.

The rate of change of momentum is proportional to the force. F = M*A. Go ahead and run the numbers, the faster lighter slide has more force. Edited November 17, 2015 by Wesquire

[metalnwood]

I dont know much about the design of pistols, I am just getting in to the sport myself but I know a little about engineering and when I saw the design and read it accounted for less recoil I thought it was based on the simple mechanism on the barrel to turn linear movement in to rotational movement.

Some of the forces that would act to push the pistol back are also rotating the barrel which hits a hard stop.

How much is absorbed I dont know but it must be something.

By that thinking, they could just make the barrel really hard to rotate and take off a ton of the recoil. It doesn't work like that. It takes very little force for the barrel to rotate. Think about it, the barrel is rotating when you rack the slide. Does it take a lot of effort to rack the slide? No, and most of that is fighting friction and the recoil spring. The rotation is nothing. It is a red herring.

I am not stating that this accounts for an appreciable amount of recoil, I was just saying what I thought was behind the design having only seen a little bit of information about it.

Making the barrel hard to rotate is exactly the opposite of what you want it to do though. You want to transfer the energy in to rotating the barrel. If you make it hard then there there is no point doing it. The easier to make the transfer of energy in to rotating the barrel the more energy you take away from it pushing the pistol directly back.

Once again, I can't say in practice how well it works, thats just how I saw it at first glance.

[busdriver02]

Ok, I think I see what you're thinking; that the lighter slide will stop in a shorter period of time than a heavier slide? If you've got something to back that up I'd love to see it.

I still don't think it matters for the recoil discussion. The time scale of that collision is going to be very,very,very small.

[busdriver02]

If the rotating barrel thing does anything, it probably very slightly delays unlocking. Which would allow some of that momentum to transfer to the shooter then, vice all at once later. Very much a guess

[Wesquire]

I dont know much about the design of pistols, I am just getting in to the sport myself but I know a little about engineering and when I saw the design and read it accounted for less recoil I thought it was based on the simple mechanism on the barrel to turn linear movement in to rotational movement.

Some of the forces that would act to push the pistol back are also rotating the barrel which hits a hard stop.

How much is absorbed I dont know but it must be something.

By that thinking, they could just make the barrel really hard to rotate and take off a ton of the recoil. It doesn't work like that. It takes very little force for the barrel to rotate. Think about it, the barrel is rotating when you rack the slide. Does it take a lot of effort to rack the slide? No, and most of that is fighting friction and the recoil spring. The rotation is nothing. It is a red herring.

I am not stating that this accounts for an appreciable amount of recoil, I was just saying what I thought was behind the design having only seen a little bit of information about it.

Making the barrel hard to rotate is exactly the opposite of what you want it to do though. You want to transfer the energy in to rotating the barrel. If you make it hard then there there is no point doing it. The easier to make the transfer of energy in to rotating the barrel the more energy you take away from it pushing the pistol directly back.

Once again, I can't say in practice how well it works, thats just how I saw it at first glance.

You are misunderstanding how energy transfer works. If it is easy to rotate, it's doing less to reduce or change recoil. If the barrel weighed 20 pounds, yeah it would have a noticeable effect.

[metalnwood]

I am not stating that this accounts for an appreciable amount of recoil, I was just saying what I thought was behind the design having only seen a little bit of information about it.

Making the barrel hard to rotate is exactly the opposite of what you want it to do though. You want to transfer the energy in to rotating the barrel. If you make it hard then there there is no point doing it. The easier to make the transfer of energy in to rotating the barrel the more energy you take away from it pushing the pistol directly back.

Once again, I can't say in practice how well it works, thats just how I saw it at first glance.

You are misunderstanding how energy transfer works. If it is easy to rotate, it's doing less to reduce or change recoil. If the barrel weighed 20 pounds, yeah it would have a noticeable effect.

I must be misunderstanding then because some of the things I have had to do in the past and calculate for involved taking rotation and converting it to linear motion. The Nm required was calculated based on the linear force I needed to overcome and mechanically works in the same way as the rotating barrel.

Having said I could be wrong, I could even be further wrong because I dont understand how saying F=ma proves that something lighter has more force? Only if a specific calculation has m*a greater would it have more force. Isnt the original force coming from the powder, the mass is the slide and the acceleration is then given from force and mass. A heaver slide will accelerate slower, but it has more mass and unless the force originally came from having less powder how does it have less force?

[Wesquire]

I am not stating that this accounts for an appreciable amount of recoil, I was just saying what I thought was behind the design having only seen a little bit of information about it.

Making the barrel hard to rotate is exactly the opposite of what you want it to do though. You want to transfer the energy in to rotating the barrel. If you make it hard then there there is no point doing it. The easier to make the transfer of energy in to rotating the barrel the more energy you take away from it pushing the pistol directly back.

Once again, I can't say in practice how well it works, thats just how I saw it at first glance.

You are misunderstanding how energy transfer works. If it is easy to rotate, it's doing less to reduce or change recoil. If the barrel weighed 20 pounds, yeah it would have a noticeable effect.

I must be misunderstanding then because some of the things I have had to do in the past and calculate for involved taking rotation and converting it to linear motion. The Nm required was calculated based on the linear force I needed to overcome and mechanically works in the same way as the rotating barrel.

Having said I could be wrong, I could even be further wrong because I dont understand how saying F=ma proves that something lighter has more force? Only if a specific calculation has m*a greater would it have more force. Isnt the original force coming from the powder, the mass is the slide and the acceleration is then given from force and mass. A heaver slide will accelerate slower, but it has more mass and unless the force originally came from having less powder how does it have less force?

Momentum is conserved, if it takes an insignificant amount to rotate the barrel, it won't have much effect. I don't know where you are coming from..

[metalnwood]

I am not going to do any maths on it so I cant say how much it would impact the recoil. Perhaps nothing of note and I wasn't stating it was. It was just my observation that based on what GP had said on a TY video about the rotating barrel helping with recoil.

I am not in an argument with you over that because I have no figures to back up what I am saying would actually contribute to less felt recoil but it does help change the direction of the force. Force is not lost but it is not all directed in the same place.

Having said all of this, I cant find where GP says this is to help reduce recoil although I thought I had seen it somewhere. So I dont see much point in debating a point if I cant see why I might be doing it

I still do not understand the F=ma thing though, the original force comes from the powder, the mass is the mass of the slide and the acceleration is calculated from those. A lighter slide therefore accelerates faster but with similar force.

[Wesquire]

I am not going to do any maths on it so I cant say how much it would impact the recoil. Perhaps nothing of note and I wasn't stating it was. It was just my observation that based on what GP had said on a TY video about the rotating barrel helping with recoil.

I am not in an argument with you over that because I have no figures to back up what I am saying would actually contribute to less felt recoil but it does help change the direction of the force. Force is not lost but it is not all directed in the same place.

Having said all of this, I cant find where GP says this is to help reduce recoil although I thought I had seen it somewhere. So I dont see much point in debating a point if I cant see why I might be doing it

I still do not understand the F=ma thing though, the original force comes from the powder, the mass is the mass of the slide and the acceleration is calculated from those. A lighter slide therefore accelerates faster but with similar force.

The deceleration when the slide hits the rear is what is at interest here. A 147gr bullet fired at 850 fps produces ~2.5Ns. This translates to a 20 oz slide moving at 4.42 m/s and a 30 oz slide moving at 2.91 m/s. If they both decelerated in .01 seconds, the force would be the same at ~248N. However, just as the recoil spring will accelerate the 20 oz slide in less time, it and the impact of the slide decelerates the 20 oz slide in less time. Let's be conservative. Assume the 20oz slide decelerates in .01 seconds and the 30 oz decelerates in .012 seconds. The force for the 30 oz slide is 206N and the 20 oz slide is 248N.

[metalnwood]

OK, I see, there are some assumed figures about it based on the acceleration of the slide when stopping.

So where does the rest of the energy come from? I mean you are quoting the force at a single instant in time as the acceleration is not a constant in this case. I think you you were to model what was happening and graph these values over time you wouldn't find such a difference as this one instance in time suggests.

[busdriver02]

What slide weighs 20 oz let alone 30?

More importantly, the entire slide traveling rearward takes around .01 seconds. The collision is probably more like .001 seconds in duration. In any event I think you're making many more assumptions than is safe at this point. How rigidly is the frame fixed in your hand? etc

The time duration of the collision is where I stopped screwing around with the equations. I couldn't convince myself there would be enough elastic deformation to make a meaningful impact on the end result.

I'm happy to assume it away, but concede that there is probably a small impact in there somewhere.

Something else occured to me

As you lighten the slide, mass of the barrel makes up a larger percentage of reciprocating mass. Which makes the barrel drop out a more significant momentum event, which is actually a very big player if I'm remembering things right. I may have to dig up that excel file....

Edited November 17, 2015 by busdriver02

[Wesquire]

What slide weighs 20 oz let alone 30?

More importantly, the entire slide traveling rearward takes around .01 seconds. The collision is probably more like .001 seconds in duration. In any event I think you're making many more assumptions than is safe at this point. How rigidly is the frame fixed in your hand? etc

The time duration of the collision is where I stopped screwing around with the equations. I couldn't convince myself there would be enough elastic deformation to make a meaningful impact on the end result.

I'm happy to assume it away, but concede that there is probably a small impact in there somewhere.

Something else occured to me

As you lighten the slide, mass of the barrel makes up a larger percentage of reciprocating mass. Which makes the barrel drop out a more significant momentum event, which is actually a very big player if I'm remembering things right. I may have to dig up that excel file....

Doesn't matter if it is 1 second or .000001 seconds. All that matters is the relative time between them. There is elastic deformation, and the heavy slide will take longer to decelerate. This spreads the impulse out. It lowers the peak force. Been saying that the whole time.

The barrel isn't reciprocating. Like I said, the barrel in a Stock 2 is effectively not moving at all. It contributes zero to the overall recoil and muzzle flip.

[busdriver02]

The barrel begins the aft travel with the slide. So you have to include that in the initial reciprocating mass to calculate slide velocity. Then the barrel drops out, leaving the rest of the slide mass to whack the frame.

I know there is elastic deformation. My point is I don't think it's significant enough to worry about. I'd have to go run some numbers, but I bet we're talking single digit power factor equivalent level of perception difference.

[Wesquire]

Funny how STI specifically doesn't market their slide cuts as doing anything for the type of muzzle flip you are describing. Now, I still would like to know why they think it reduces forward recoil, but at least they have acknowledged that slide lightening does nothing beneficial for muzzle flip as we are describing.

http://stiguns.com/guns/dvc-limited/

http://stiguns.com/guns/dvc-open/

Edited November 17, 2015 by Wesquire

[Wesquire]

The barrel begins the aft travel with the slide. So you have to include that in the initial reciprocating mass to calculate slide velocity. Then the barrel drops out, leaving the rest of the slide mass to whack the frame.

I know there is elastic deformation. My point is I don't think it's significant enough to worry about. I'd have to go run some numbers, but I bet we're talking single digit power factor equivalent level of perception difference.

As the slo-mo videos show, there's basically no flip in the gun until the slide hits the rear, the barrel stops moving well before that time with NO impact on the muzzle flip. Transfer of momentum is transfer of momentum, if there was a significant transfer at the point of the barrel dropping out, you'd see it in flip. Again, it doesn't matter how much deformation there is...both slides would cause a theoretically equal amount of deformation. However, the slower slide will travel that deformed distance slower...thus the impact is spread out more.

Edited November 17, 2015 by Wesquire

[metalnwood]

The barrel begins the aft travel with the slide. So you have to include that in the initial reciprocating mass to calculate slide velocity. Then the barrel drops out, leaving the rest of the slide mass to whack the frame.

I know there is elastic deformation. My point is I don't think it's significant enough to worry about. I'd have to go run some numbers, but I bet we're talking single digit power factor equivalent level of perception difference.

As the slo-mo videos show, there's basically no flip in the gun until the slide hits the rear, the barrel stops moving well before that time with NO impact on the muzzle flip. Again, it doesn't matter how much deformation there is...both slides would cause a theoretically equal amount of deformation. However, the slower slide will travel that deformed distance slower...thus the impact is spread out more.

I just looked at the first video I saw, every one has the muzzle coming up before the slide hits the back.

I do agree that the slide has taken a lot of the force so the real kick is when it hits the back.

I am not sure how much peak force really matters here. At the end of the day, the whole shot it over in a very similar amount of time and the forces are averaged over that time.

I have seen a lot of telemetry from cars and I can tell you a number of cars e.g. a dallara indycar might show 70Nm force through the wheel, at such a small amount of time it is not noticed but it may have happened. Finding such a number in an instant of time rarely tells the whole story.

[busdriver02]

Actually the lighter slide should cause less deformation. We're well onto the material science part, and I flushed that stuff years ago.

The powder burning and bullet leaving the barrel happens before the barrel unlocks. So the slide is moving at full speed with barrel still attached. The barrel's momentum does get transfered to the frame, just in a way that doesn't contribute to a tendency for muzzle rise. It acts more through the center of mass of the pistol, unlike the slide.

Most guns with heavy slides are just plain heavy guns.

[Wesquire]

The barrel begins the aft travel with the slide. So you have to include that in the initial reciprocating mass to calculate slide velocity. Then the barrel drops out, leaving the rest of the slide mass to whack the frame.

I know there is elastic deformation. My point is I don't think it's significant enough to worry about. I'd have to go run some numbers, but I bet we're talking single digit power factor equivalent level of perception difference.

As the slo-mo videos show, there's basically no flip in the gun until the slide hits the rear, the barrel stops moving well before that time with NO impact on the muzzle flip. Again, it doesn't matter how much deformation there is...both slides would cause a theoretically equal amount of deformation. However, the slower slide will travel that deformed distance slower...thus the impact is spread out more.

I just looked at the first video I saw, every one has the muzzle coming up before the slide hits the back.

I do agree that the slide has taken a lot of the force so the real kick is when it hits the back.

I am not sure how much peak force really matters here. At the end of the day, the whole shot it over in a very similar amount of time and the forces are averaged over that time.

I have seen a lot of telemetry from cars and I can tell you a number of cars e.g. a dallara indycar might show 70Nm force through the wheel, at such a small amount of time it is not noticed but it may have happened. Finding such a number in an instant of time rarely tells the whole story.

The spring resistance and friction are probably causing nearly all the muzzle rise you see.

[busdriver02]

Or flinch.

[Wesquire]

Actually the lighter slide should cause less deformation. We're well onto the material science part, and I flushed that stuff years ago.

The powder burning and bullet leaving the barrel happens before the barrel unlocks. So the slide is moving at full speed with barrel still attached. The barrel's momentum does get transfered to the frame, just in a way that doesn't contribute to a tendency for muzzle rise. It acts more through the center of mass of the pistol, unlike the slide.

Most guns with heavy slides are just plain heavy guns.

Less deformation would mean more impact force. The barrel has no relevant momentum. It is just free falling like 2 mm. Other than that, there's a completely negligible amount of friction on the lugs when unlocking.

[busdriver02]

It's not the drop that matters. It starts as part of the free recoiling mass. So it's mass gets included when you calculate the velocity of the recoiling slide. When it drops out, it basically just goes away for the purpose of this discussion. This is a safe if inaccurate assumption based on no observed muzzle rise in videos when this happens.

This is the key part of making a slide lighter.

[Wesquire]

It's not the drop that matters. It starts as part of the free recoiling mass. So it's mass gets included when you calculate the velocity of the recoiling slide. When it drops out, it basically just goes away for the purpose of this discussion. This is a safe if inaccurate assumption based on no observed muzzle rise in videos when this happens.

This is the key part of making a slide lighter.

Why would its mass be included in the calculation of slide velocity? It is not fixed to the slide anymore than the frame is. It is only relevant to the extent of its friction with the slide. What is the key part?

Edited November 17, 2015 by Wesquire