CoalTrain49
Member
Sighted in. Probably high and right.
Every shooter sights in a rifle to a different POA/POI.
Every shooter sights in a rifle to a different POA/POI.
Where Do Rifles Shoot By Themselves?
- Thread starter Bart B.
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Orcon
Member
This.
More importantly, if a rifle fires an aggregate in the forest does it make a group?
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I think there's two basic schools of thought in this conundrum:
One is the rifle and bore stays motionless until the bullet leaves the barrel.
The other is the rifle and bore axis starts moving before the bullet leaves the barrel.
Are Newton's laws applicable?
One is the rifle and bore stays motionless until the bullet leaves the barrel.
The other is the rifle and bore axis starts moving before the bullet leaves the barrel.
Are Newton's laws applicable?
Orcon
Member
Classical physics describes mechanics to a fairly accurate degree. I would have to say that as soon as [EDIT in bold] powder gas accelerates the bullet and then when it engages the rifling there is a transfer of energy and that system, therefor, begins to move accordingly at that point.
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herrwalther
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I can have multiple answers for this trick sounding question.
The gun control activist would say the rifle shoots through a school, killing 350 children and a bunny.
If I am not touching the rifle at all, it won't be firing.
If it is somehow fired remotely, without being behind it, the round should go up and to the right some distance off target based on a few dozen factors.
The gun control activist would say the rifle shoots through a school, killing 350 children and a bunny.
If I am not touching the rifle at all, it won't be firing.
If it is somehow fired remotely, without being behind it, the round should go up and to the right some distance off target based on a few dozen factors.
CoalTrain49
Member
If an AR fires itself in the forest and Nancy Pelosi isn't there to hear it, does it still need to be banned?
bikemutt
Member
I'll take a shot at it, the bullets should hit low of POA. Without any significant external forces, a cylindrical barrel/breach should launch the bullet straight ahead. With an opposing force below the bore axis (buttstock to shoulder), I'd expect the muzzle to rise at some rate, perhaps enough to nudge the bullet upwards.
RugerOldArmy
Member
Wouldn't it matter how the rifle was shot zeroing it?
If they zeroed it free recoil...it should shoot POA...for there was no change.
If it wasn't, then it would depend on RH or LH twist, harmonics, and any tilt/cant under recoil, based on how it was fired when zeroed, that isn't there when shot, now, in a free recoil fashion.
No?
If they zeroed it free recoil...it should shoot POA...for there was no change.
If it wasn't, then it would depend on RH or LH twist, harmonics, and any tilt/cant under recoil, based on how it was fired when zeroed, that isn't there when shot, now, in a free recoil fashion.
No?
RugerOldArmy
Member
We already know that harmonics comes into play, and the rifle/bore doesn't stay motionless. At least, that is what I firmly believe.
But I've been wrong before. Have I ever mentioned my first wife?
Orcon
Member
Low and in a fashion corresponding to the twist at a rate of inverse square.
Rifling twist issues have been part of this thread.
How much does spin drift at 100 yards change across twist rates from 1:10 to 1:13 for a given bullet? How easy is it to discriminate the difference by shooting?
Pick one, then guess or calculate the difference from one of the on line sources.
How much does spin drift at 100 yards change across twist rates from 1:10 to 1:13 for a given bullet? How easy is it to discriminate the difference by shooting?
Pick one, then guess or calculate the difference from one of the on line sources.
Less than 4 inches at a thousand yards*.
Taking Bart's claim that groups open up 20% per 100 yards past 100 yards, we can work backwards to calculate that the difference at 100 yards will be under 0.08". That difference would be tough to discern in any statistically valid way, methinks.
*155gr .308 SMK @ 2900fps MV
zb338
Member
The rifle will miss the target and then clean itself and put itself
away in it's case.
Z
away in it's case.
Z
MachIVshooter
Member
The torque imparted by a bullet due to rifling is truly insignificant. As in tenths of inch pounds, which is acting against the inertial mass of several pounds of rifle, and only for a few milliseconds.
For a Sierra 30 caliber 155-gr leaving at 2900 zeroed at 1000, spin drift?
JBM ballistics calculates 7.7 inches for their typical 1:13" twist.
For a 1:10" twist, 10.6 inches.
Both twists' drift at 100 yards, less than 0.1 inch.
JBM ballistics calculates 7.7 inches for their typical 1:13" twist.
For a 1:10" twist, 10.6 inches.
Both twists' drift at 100 yards, less than 0.1 inch.
Newtosavage
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Oooh. An interesting reply. One I hadn't thought of. But since the mass of the stock is still below the line of the bore, wouldn't it still kick up?
nowhere, sans a bizarre malfunction
Nature Boy
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The answer to that is:
Yes, no and all states in between, until outside observation fixes the state. Classic "Schrodingers Cat" paradox
https://en.wikipedia.org/wiki/Schrödinger's_cat
Here's a program to calculate bullet departure angles from a free recoiling rifle in space:
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
This model assumes that the rifle is essentially in free space and unconstrained by any rests or clamps as it recoils. Shooting a rifle off bags is a fair approximation to this. However, if small caliber rifle is gripped tightly or pulled hard into the shoulder then the recoil dynamics could be affected.
It's based on the 308 Win cartridge so use 1.1 to 1.3 millisecond barrel times to mark the bullet exit point on the barrels vertical whip axis. Same thing happens horizontally with center of holding mass to the side.
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
This model assumes that the rifle is essentially in free space and unconstrained by any rests or clamps as it recoils. Shooting a rifle off bags is a fair approximation to this. However, if small caliber rifle is gripped tightly or pulled hard into the shoulder then the recoil dynamics could be affected.
It's based on the 308 Win cartridge so use 1.1 to 1.3 millisecond barrel times to mark the bullet exit point on the barrels vertical whip axis. Same thing happens horizontally with center of holding mass to the side.
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Orcon
Member
Ah yes, the ol' superposition principle. Awwww, you collapsed my wave function that coulda been a good group!
lysanderxiii
Member
Somewhere in the circular probable error for that rifle, with the circle centered on the point of aim.
splattergun
Member
this answers the 'how to pull the trigger" portion of the question.
http://hyskore.com/products/30010-hydraulic-trigger-release/
A few years back I saw an old boy running one of them at the range. His rifle was mounted in a Lead Sled. HIs POI was high center. THe only time he touched the rifle was to operate the bolt.
What I observed was the way he sighted was to simply bend over and look through the scope and adjust the Sled. I can't believe that it would be possible to achieve the same perspective through the scope vs if he were holding it to his shoulder. But the hyskore tool and Sled removed the human variable from grip, mount and trigger pull. Though off the bull, he was getting very consistent POI.
http://hyskore.com/products/30010-hydraulic-trigger-release/
A few years back I saw an old boy running one of them at the range. His rifle was mounted in a Lead Sled. HIs POI was high center. THe only time he touched the rifle was to operate the bolt.
What I observed was the way he sighted was to simply bend over and look through the scope and adjust the Sled. I can't believe that it would be possible to achieve the same perspective through the scope vs if he were holding it to his shoulder. But the hyskore tool and Sled removed the human variable from grip, mount and trigger pull. Though off the bull, he was getting very consistent POI.
I never liked sighting in a rifle like that, as they shoot to a different POI when held. I have seen two different people shooting free hand, both of whom were good shots, who both shot to a slightly different POI using the same rifle, simple because of their mechanics. But they could both repeat those mechanics well, so could shoot well. I have seen some people sighting in for deer season that just make me shake my head due to horrible mechanics. Poor buggers don't have much of a chance at anything at any distance.
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