200 vs. 230gr .45 ACP's
- Thread starter Brutus
- Start date
Just to be clear, all the boreline-sightline measurements I've done have been on linkless designs because that's what I have on hand.
I'd be interested to see a boreline-sightline comparison on a linked design. That would tell pretty quickly if there's something significantly different going on. Because the link starts moving the barrel breech downward as soon as recoil starts, there is potential for it to behave differently. That's why I added the caveat about designs with links in my first post on this thread.
I'd be interested to see a boreline-sightline comparison on a linked design. That would tell pretty quickly if there's something significantly different going on. Because the link starts moving the barrel breech downward as soon as recoil starts, there is potential for it to behave differently. That's why I added the caveat about designs with links in my first post on this thread.
And there's friction between the locking lugs and their corresponding recesses in the slide that act a little like glue, briefly.
On review, there are a few things off in the analysis compared to my own measurements. Recoil rotation around the wrist all happens long after the bullet is gone. Your hand has mass, too and takes awhile to start moving. Most of the rotation that occurs while the bullet is in the bore happens by compression of the flesh of the palm. Because of the difference in grip shapes, for the m.1911, pushing on the muzzle shows an axis of rotation in that flesh happens about 2 inches below the bore line with a flat mainspring housing, and with the arched A1 housing about 1¾" below the bore line in my hands. On my Smith 25-2 its grip panel frame drops the center to about 3" below the bore line, so there is 1.7 times more torque from the revolver just from that. The test ignores the difference in barrel length, but I measure it to be almost 1.6 times more bullet travel in the revolver (4.35" in the 5" 1911, and 6.851" in the 6" 25-2). The velocities are about the same, due to the barrel/cylinder gap.
Of purely academic interest: I can only find gap data on 38 caliber pistols, but when I average it out, a typical gap will probably cost you about 8% from MV by dropping pressure. That means both guns will produce close to the same velocities, but the barrel times are not the same. The 1911 is about 0.76 ms when I carefully tweak QuickLOAD to get a match to measured data with Universal. The revolver then has 1.16 ms of barrel time. The average force is different, too. For the 1911 it is about 977 lbs average, while for the revolver it is about 617 lbs. But this paragraph doesn't matter much in the practical world because, as long as the final velocities are the same, the equal and opposite momentum imparted during the time the bullet is in the barrel will be the same. I got 830 fps for the pistol and 836 fps for the revolver, but the latter is based on that 8% estimate for the gap loss, so it can't be assumed to be precise.
Bottom line is that angular momentum resulting from torque during barrel time is exaggerated for the revolver by the difference in rotation axis (moment of inertia), a factor of about 1.7. Nonetheless, it is true, looking at the bore sighter's laser spot from a properly centered boresight, that there is little difference in the pistol bore line and sight line at 50 feet. And yet, here we go back to the OP and find that annoying, but real 2" change in POI. I still get a disproportionately large difference in recoil feel and muzzle jump. I still don't know what range the OP is shooting at, but at 25 yards it is only about 14 thousandths of an inch of muzzle elevation to get a 2" change in POI, and for me, with iron sights, the blur area looking at the bore sighter's Green spot is at least that big.
Some new experimental results will be interesting, but it may take lining up some targets at 7, 25 and 50 yards and shooting through all three at once and looking at group centers in all three to get a clear picture of what is due to recoil and what is due to bullet fall. It's making for a good mental exercise.
On review, there are a few things off in the analysis compared to my own measurements. Recoil rotation around the wrist all happens long after the bullet is gone. Your hand has mass, too and takes awhile to start moving. Most of the rotation that occurs while the bullet is in the bore happens by compression of the flesh of the palm. Because of the difference in grip shapes, for the m.1911, pushing on the muzzle shows an axis of rotation in that flesh happens about 2 inches below the bore line with a flat mainspring housing, and with the arched A1 housing about 1¾" below the bore line in my hands. On my Smith 25-2 its grip panel frame drops the center to about 3" below the bore line, so there is 1.7 times more torque from the revolver just from that. The test ignores the difference in barrel length, but I measure it to be almost 1.6 times more bullet travel in the revolver (4.35" in the 5" 1911, and 6.851" in the 6" 25-2). The velocities are about the same, due to the barrel/cylinder gap.
Of purely academic interest: I can only find gap data on 38 caliber pistols, but when I average it out, a typical gap will probably cost you about 8% from MV by dropping pressure. That means both guns will produce close to the same velocities, but the barrel times are not the same. The 1911 is about 0.76 ms when I carefully tweak QuickLOAD to get a match to measured data with Universal. The revolver then has 1.16 ms of barrel time. The average force is different, too. For the 1911 it is about 977 lbs average, while for the revolver it is about 617 lbs. But this paragraph doesn't matter much in the practical world because, as long as the final velocities are the same, the equal and opposite momentum imparted during the time the bullet is in the barrel will be the same. I got 830 fps for the pistol and 836 fps for the revolver, but the latter is based on that 8% estimate for the gap loss, so it can't be assumed to be precise.
Bottom line is that angular momentum resulting from torque during barrel time is exaggerated for the revolver by the difference in rotation axis (moment of inertia), a factor of about 1.7. Nonetheless, it is true, looking at the bore sighter's laser spot from a properly centered boresight, that there is little difference in the pistol bore line and sight line at 50 feet. And yet, here we go back to the OP and find that annoying, but real 2" change in POI. I still get a disproportionately large difference in recoil feel and muzzle jump. I still don't know what range the OP is shooting at, but at 25 yards it is only about 14 thousandths of an inch of muzzle elevation to get a 2" change in POI, and for me, with iron sights, the blur area looking at the bore sighter's Green spot is at least that big.
Some new experimental results will be interesting, but it may take lining up some targets at 7, 25 and 50 yards and shooting through all three at once and looking at group centers in all three to get a clear picture of what is due to recoil and what is due to bullet fall. It's making for a good mental exercise.
polyphemus
New member
Thank you Uncle Nick
I have done extensive reading on the flat bottomed stop plate and haven't seen any data regarding the actual amount of additional force required to cock the hammer, I don't have the math so your figures stand,25%.
John I was disappointed to read you hold Browning to be wrong.
He was the greatest american gunsmith,bar none and he knew firearms and their workings better than most of us will ever do his patent descriptions were written by his attorneys but they are true to the facts and to this day stand to
any objective scrutiny.
And one factor for you to include, the barrel is dragged along by the bullet and held fastened to the crosspin while it exits,this also contributes to the delay.
The slide needs V to have momentum and this is gained after it travels all of 1/10".Browning knew.
I have done extensive reading on the flat bottomed stop plate and haven't seen any data regarding the actual amount of additional force required to cock the hammer, I don't have the math so your figures stand,25%.
John I was disappointed to read you hold Browning to be wrong.
He was the greatest american gunsmith,bar none and he knew firearms and their workings better than most of us will ever do his patent descriptions were written by his attorneys but they are true to the facts and to this day stand to
any objective scrutiny.
And one factor for you to include, the barrel is dragged along by the bullet and held fastened to the crosspin while it exits,this also contributes to the delay.
The slide needs V to have momentum and this is gained after it travels all of 1/10".Browning knew.
polyphemus
New member
ok,USSR get us out of the paralysis
What have you got?
What have you got?
I think if you read my statement more carefully you will see that I believe he was simplifying the explanation and that is what resulted in the discrepancy that is present if the statement is taken literally.
Clearly the movement of the slide and barrel is not delayed until after the bullet leaves the bore--that's not possible, it contradicts the laws of physics, and we have ultra-slow motion video to prove that the parts do move. But the movement is slowed sufficiently by the design to delay unlocking until after the bullet leaves the bore.
All the momentum is gained while the bullet is in the bore. Something that would be impossible if the movement of the parts were literally delayed until the bullet exits.
This is all factored into the system by taking conservation of momentum into account. The momentum of the ejecta (which is affected by the friction between the bullet and the barrel) is all you need to know to determine the momentum of the recoiling mass. NOT because the bullet/barrel friction can be neglected, but because it is already taken into account when one looks at the momentum figures.
Some people are satisfied knowing results. Others want to know exactly why the results turn out the way they do.
There's nothing wrong with either point of view. A car doesn't get a person from point A to point B any better if the person understands the intricate details of internal combustion engine operation, nor will failing to fully comprehend the design of an automatic transmission make a person unable to drive.
That said, it is important that at least some people do have that knowledge.
I'm pretty sure that Browning knew what he was talking about. I am less sure that the wording he used describing these things cannot be dis-assembled and re-assembled by "barracks lawyers" to make it appear that Browning didn't know what he was talking about, or to make it seem he said something he didn't, or didn't intend.
We've been all over in this thread, but the original question was about how to get the lighter 200gr slugs to impact the same point as the 230gr ones at the given range.
My idea was to match the 200gr and 230 gr velocities, so that they both had the same amount of "time in the barrel".
Can we all agree that recoil, as a force, begins at the moment of bullet movement? And that since it is happening as the bullet travels down the barrel, that it has an effect on the position of the muzzle at the instant the bullet exits?? That the barrel of a handgun is rising as the bullet accelerates down the bore?
I think we can discuss how much movement there is, and how important, or not, it is, but only after we agree that it is there.
and that, therefore, two bullets spending the same amount of time in the rising barrel, and that barrel rising at the same approximate rate for both bullets, should have the same approximate point of impact at close range before factors outside the barrel exert their effect. Does this seem reasonable to you?
I think discussion of what else the barrel, slide and gun are doing at the same time or immediately afterwards doesn't address the original question.
or are we just arguing about how many angels can dance on the head of a pin?
We've been all over in this thread, but the original question was about how to get the lighter 200gr slugs to impact the same point as the 230gr ones at the given range.
My idea was to match the 200gr and 230 gr velocities, so that they both had the same amount of "time in the barrel".
Can we all agree that recoil, as a force, begins at the moment of bullet movement? And that since it is happening as the bullet travels down the barrel, that it has an effect on the position of the muzzle at the instant the bullet exits?? That the barrel of a handgun is rising as the bullet accelerates down the bore?
I think we can discuss how much movement there is, and how important, or not, it is, but only after we agree that it is there.
and that, therefore, two bullets spending the same amount of time in the rising barrel, and that barrel rising at the same approximate rate for both bullets, should have the same approximate point of impact at close range before factors outside the barrel exert their effect. Does this seem reasonable to you?
I think discussion of what else the barrel, slide and gun are doing at the same time or immediately afterwards doesn't address the original question.
or are we just arguing about how many angels can dance on the head of a pin?
Whether we all agree or not, there is video to support that assertion and it is consistent with the laws of physics.
It certainly has some effect in real-world guns, but it seems clear that in some designs the effect is not significant--that is, the muzzle moves, but the only significant motion of the muzzle while the bullet is in the bore is straight backwards. And that it therefore does not result in any significant change in the point of impact.
That's really the crux of the whole discussion at this point.
That's pretty much what's happening.
Jim Watson
New member
Not really.
First run 1911 firing pin stops had a 5/64" bottom corner radius, Army redo was 7/32".
The square bottom was introduced by EGW "so the customer can adjust" and probably not coincidentally, cheaper to make.
Use of the square bottom part as delivered appears to be in accordance with that fine Internet Logic, if a smaller radius is better, no radius must be best.
polyphemus
New member
Neither Browning nor I say that the slide does not start to move rearward when the bullet begins its own forward motion,the snide remarks aside.
We are talking about an extremely short event here,about a milisecond and less than a 1/8" travel length.The slide begins to move and for the first.005"only mass,friction and springs oppose it then the grooves contact the barrel ribs and
begin to drag it back here the slide meets barrel inertia and resistance from the bullet's forward impulse to the barrel,the link begins to rotate back and as the bullet exits and pressure is released the link pulls the barrel down and out of the way.
We are talking about an extremely short event here,about a milisecond and less than a 1/8" travel length.The slide begins to move and for the first.005"only mass,friction and springs oppose it then the grooves contact the barrel ribs and
begin to drag it back here the slide meets barrel inertia and resistance from the bullet's forward impulse to the barrel,the link begins to rotate back and as the bullet exits and pressure is released the link pulls the barrel down and out of the way.
polyphemus
New member
Thank you for the remainder 44
All done.
All done.
You deserve an apology for my snide remark , sorry about that . I had to look up the definition to be sure I understood the word correctly . Although my statement was snide it was meant in jest rather then malice . I almost never mean to be rude or condescending , most of my post are in a jovial manner but don't always come across that way when written out .
Again sorry about that
MG
Been following the whole thread.
Did some shooting today.
5" Dan wesson Vaor 45, stock form.
Shot target loads and hot loads along with one target with Remington Factory 230 Ball.
Results...........
Top left 185 Jacketed HP with minimal powder probably 700 fps. Did not eve work the action. I only had 2.
Top right my target load. 200 SWC at 675 fps.
Bottom left, 200 SWC, 7.0 Unique 900 fps
Bottom right a new load I tried today. 8.0 CFE Pistol 200 SWC, should be 1100 fps. Not chronographed, but ..... Max is 8.2 grains on Hodgun website for 1142 fps.
Center Reimington factory Ball.
Gun was rested on sand bags.
Distance 25 yards.
Sight Burris FF III NO adjustments made.
Make your own conclusion.
David
I did some quick math. Bullet goes from zero to 850 fps in 5 inches.
850 Feet * 12 inches = 9600 inches per second. Divide that by 5 inches and get 1900th of a second for barrel time.
It IS a little longer, but I dont get into math that deep to figure acceleration.
The barrel and slide do move back in that .0019 of a second. Some one else can figure the distance the slid moves in that little time. I have seen vidieo of the slide moving before the bullet exits. The slide and barrel move together, so elevation does not change.
David
Did some shooting today.
5" Dan wesson Vaor 45, stock form.
Shot target loads and hot loads along with one target with Remington Factory 230 Ball.
Results...........
Top left 185 Jacketed HP with minimal powder probably 700 fps. Did not eve work the action. I only had 2.
Top right my target load. 200 SWC at 675 fps.
Bottom left, 200 SWC, 7.0 Unique 900 fps
Bottom right a new load I tried today. 8.0 CFE Pistol 200 SWC, should be 1100 fps. Not chronographed, but ..... Max is 8.2 grains on Hodgun website for 1142 fps.
Center Reimington factory Ball.
Gun was rested on sand bags.
Distance 25 yards.
Sight Burris FF III NO adjustments made.
Make your own conclusion.
David
I did some quick math. Bullet goes from zero to 850 fps in 5 inches.
850 Feet * 12 inches = 9600 inches per second. Divide that by 5 inches and get 1900th of a second for barrel time.
It IS a little longer, but I dont get into math that deep to figure acceleration.
The barrel and slide do move back in that .0019 of a second. Some one else can figure the distance the slid moves in that little time. I have seen vidieo of the slide moving before the bullet exits. The slide and barrel move together, so elevation does not change.
David
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Am thinking we need some person way smarter than i to set up a poll, based on the average poi difference between the loads in USSR's test. Something like 1 in or less, than 1 to 2 in and more than 2 inch.
1 in or less = ain't squat
1 to 2 in = little more than ain't squat, adjust sights/hold for 50 yds
over 2 in = adjust the sights for differing load, or adjust load for smaller poi
Then we need a prize?
Am in for ain't squat, and already know how far i can p_ss in the snow.
MERRY CHRISTMAS!
1 in or less = ain't squat
1 to 2 in = little more than ain't squat, adjust sights/hold for 50 yds
over 2 in = adjust the sights for differing load, or adjust load for smaller poi
Then we need a prize?
Am in for ain't squat, and already know how far i can p_ss in the snow.
MERRY CHRISTMAS!
Part of the problem with small changes is determining the statistical significance of the group to try to discern what is real. It may need 30-shot groups (or combining 3 10-shot groups) to do it. I couldn't conclude anything from the small groups trying to distinguish real from random. We still don't know what the OP's range was. We also don't know if the bag stabilized movement of the gun.
David,
850 ft/s times 12 in is 850 ft²/s or 10,200 in²/s.
For 850 ft/s (or any other velocity) the bullet starts out at 0 ft/s, so the average velocity inside the barrel is the average of 0 ft/s and the MV. In this case 0 ft/s and 850 ft/s, or 425 ft/s. The barrel may be 5 in. long, but the bullet sits forward in the case and has bullet base travel of about 4.35 in. to the muzzle.
4.35 in/12 in/ft = 0.3625 ft
In order to get the feet to cancel out and leave seconds, you have to divide that distance by the mean velocity:
0.3625 ft / 425 ft/s = 8.53 × 10⁻⁴ s, or 0.000853 seconds.
So, a bit less than a thousandth of a second. In reality, that time is a little long. The reason is the peak pressure occurs when the bullet is only half an inch so into the throat, and the peak pressure gives it a third to half its speed by the time it has gone an inch, so it starts down the rest of the barrel with speed already approaching the average velocity and getting faster from there. It will vary with the powder burn rate because that determines how far forward the bullet is at its peak, but it looks like, for a fast powder like Bullseye, the actual barrel time would be around a tenth of a millisecond shorter than that calculation gives.
David,
850 ft/s times 12 in is 850 ft²/s or 10,200 in²/s.
For 850 ft/s (or any other velocity) the bullet starts out at 0 ft/s, so the average velocity inside the barrel is the average of 0 ft/s and the MV. In this case 0 ft/s and 850 ft/s, or 425 ft/s. The barrel may be 5 in. long, but the bullet sits forward in the case and has bullet base travel of about 4.35 in. to the muzzle.
4.35 in/12 in/ft = 0.3625 ft
In order to get the feet to cancel out and leave seconds, you have to divide that distance by the mean velocity:
0.3625 ft / 425 ft/s = 8.53 × 10⁻⁴ s, or 0.000853 seconds.
So, a bit less than a thousandth of a second. In reality, that time is a little long. The reason is the peak pressure occurs when the bullet is only half an inch so into the throat, and the peak pressure gives it a third to half its speed by the time it has gone an inch, so it starts down the rest of the barrel with speed already approaching the average velocity and getting faster from there. It will vary with the powder burn rate because that determines how far forward the bullet is at its peak, but it looks like, for a fast powder like Bullseye, the actual barrel time would be around a tenth of a millisecond shorter than that calculation gives.