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Do bullets fly in a straight line?


IHAVEGAS

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While working up loads, typically 9mm or 40 pistol,  there have been occasions where the following seemed to be true:

 

1. Sandbag results at 10 yards have been excellent.

 

2. Sandbag results at 20 yards or beyond have been worse than expected given the 10 yard results. For example, if I shot a 1" group at 10 yards I would have expected to get something like a 2" group at 20 yards but perhaps what I got was a 3" or worse group.   

 

So far my figuring on this (discounting random error due to covfefe) has been that the increased amount of error has all been due to the shooter. Got to wondering though, if some of the increased error might be related to something like an improper amount of bullet spin or deformation (lack of roundness) of the bullet with the particular gun/load recipe. 

 

Thoughts?

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So many possibilities:

 

 - sighting error - are you over 50 years old?

 - pushing the bullet too hard (too fast) -

 - poor quality bullets

 - poor fitting bullets

 

Lighting conditions -

 

Just some random thoughts   :) 

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2 hours ago, IHAVEGAS said:

if I shot a 1" group at 10 yards I would have expected to get something like a 2" group at 20 yards

 

If that was true, there would be no reason to ever test ammo or guns past 10 yds.

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Bullets oscillate as they pass theough the speed of sound (entering they will be stabilized by the barrel but not while exiting jn flight) which can affect group size.  Obviously more of an issue with rifles but it's something to consider with pistols as well.  

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2 hours ago, TDA said:

 

If that was true, there would be no reason to ever test ammo or guns past 10 yds.

 

I always need to stretch the distance in order to feel like I have point of impact as close to point of aim as I can get it. 

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14 minutes ago, kneelingatlas said:

What brand of bullets are you shooting?  It sounds like my experience with Xtremes in my Open gun: tight groups at 10 yards, shotgun at 20.  I shoot Montana Gold now :cheers:

 

SNS most recently, but I meant it as a generic question. 

 

Had always been thinking along the lines that errors beyond what was expected at the longer distances were all about shooter error, but then got to wondering if there was more going on. 

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4 hours ago, IHAVEGAS said:

 

SNS most recently, but I meant it as a generic question. 

 

Had always been thinking along the lines that errors beyond what was expected at the longer distances were all about shooter error, but then got to wondering if there was more going on. 

Ballistics is a science/art that is sometimes difficult to understand. There are plenty of resources online about this subject. Lots of things affect the flight of a bullet, these get magnified with distance, some of the factors are (not necessarily in order of importance).

1. Gravity: As the bullet flies it travels in an arc, eventually hitting the ground

2. Wind: This pulls (or pushes) the bullet off the point of aim

3. Stability of the shooters hold

4. Speed of the bullet

5. Weight of the bullet

6. Rotation of the earth

 

Conclusion, lots of stuff affect accuracy, I try to restrict my shooting to the closer targets, my eyes aren't as good as they once were. ;)

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4 minutes ago, lefty o said:

bullets arent magic, they fly in whichever direction the firearm was pointed when the bullet left the bore. and as always they start dropping once they leave the barrel.

 

Baseballs aren't magic either, but there is much to do with surface roughness and spin. 

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5 hours ago, IHAVEGAS said:

 

SNS most recently, but I meant it as a generic question. 

 

Had always been thinking along the lines that errors beyond what was expected at the longer distances were all about shooter error, but then got to wondering if there was more going on. 

 

Yes, there is more going on.  Any inconsistencies in the shape or center of gravity in the bullets effect accuracy to a greater degree as distance increases.

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Not all load/firearm combinations are created equally.  

Using a sand bag rest at 25 yards is more revealing than at 10 yards.  

If you're new to this, try some factory target ammo, or maybe even some high grade 22 rimfire stuff out of a good rimfire pistol.

Once you can get good tight concentric groups at 25 yds over a rest, then you can take some of the human error out of the problem.

Only then can you properly evaluate reloaded ammo.

But with a handgun at 20 yards off of a rest, the only issues should be you and the quality of the ammo you are shooting.

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2 hours ago, lefty o said:

bullets arent magic, they fly in whichever direction the firearm was pointed when the bullet left the bore. and as always they start dropping once they leave the barrel.

 

then please explain why there is so much difference in group sizes when comparing different bullets and powders. 

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1 hour ago, superdude said:

 

then please explain why there is so much difference in group sizes when comparing different bullets and powders. 

internal ballistics, external ballistics, harmonics, etc etc, and lets not forget the imperfect guy shooting the gun. a lot of what ifs, but if you really want to have the basics, read "understanding firearm ballistics" by robert a. rinker . mind numbing read, but youll have the basics.

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Do bullets fly in a straight line?

 

 

No, they do not.

 

The difference in group size is most likely due to the shooter.  Sure pistol sights are not great for long range accuracy work but that doesn't really make the pistol in accurate, just harder to aim.  If the ammunition does better when fired from the same pistol in a machine rest, it was the person firing it that made it inaccurate.

 

Maybe get a carbine in the same caliber and see if you are like most everyone else and more accurate with a rifle than a pistol.  Optics on a pistol can also improve accuracy.  They don't make the pistol mechanically more accurate just give you better resolution of where you are aiming and that makes things more repeatable shot after shot.

 

Not all "optics" are the same either. Take these three for example, which do you think you could Have the best chance of aiming at the same spot over and over?

 

IMG_20161107_131710_812_zpso5jldjxs.jpg

 

IMG_20161107_131755_028_zpssb8ofvw7.jpg

 

IMG_20161107_141610_673_zpsaxjpfhfc.jpg

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7 hours ago, lefty o said:

internal ballistics, external ballistics, harmonics, etc etc, and lets not forget the imperfect guy shooting the gun. a lot of what ifs, but if you really want to have the basics, read "understanding firearm ballistics" by robert a. rinker . mind numbing read, but youll have the basics.

Huge +1 on thr Rinker book.  I've read it multiple times.  I find it to be an enjoyable read, actually.  

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On 6/1/2017 at 8:13 AM, Hi-Power Jack said:

So many possibilities:

 

 - sighting error - are you over 50 years old?

 - pushing the bullet too hard (too fast) -

 - poor quality bullets

 - poor fitting bullets

 

Lighting conditions -

 

Just some random thoughts   :) 

 

on a semi auto pistol you also have barrel fit/lockup that can effect group size as well 

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  • 2 weeks later...

Ransom rest helps to separate the firearm accuracy from shooter held accuracy.  Really best way to check load accuracy, real good position on a bench is second best.

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  • 2 weeks later...

Improper trigger control along with sub par fundamentals will throw a shot more than anything. At 25yds you don't need to worry about corrielas. Proper trigger control and sight alignment are the keys.

Sent from my SM-N920V using Tapatalk

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The projectile tries to go where you point it, but then gravity and drag take over  based on the ballistic co-efficient. But at typical pistol distance, to 40 yards, no, that's all shooter. 

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10 yards is not enough distance to really check accuracy.  The bullet doesn't have enough time to stabilize at that distance and will therefore give you different groups as you go further down range.  Just changing powder or bullet OAL can improve the groupings. 

 

In archery we would test our groups at the furthest distance needed and them shoot closer until we reached the nearest distance, Usually 90 meters down to 30 meters.   Arrows that would shoot all in the gold at 30 meters with one setting would rarely shoot all golds at 90 so we would have to re-tune them.

 

Pistol and rifle shooting is no different.  Finding the perfect bullet takes a lot more effort than just copying a load.  You have to test it in your gun.

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  • 2 weeks later...

Why are you testing at 10 yards. 25 yards is the standard. 10 yards is rock throwing range. With pistols I don't bench them for accuracy testing or zeroing. I find that its easier just to shoot them off hand. Your point of impact off a bag will be different than it is in your hands. 
Pat

 

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  • 1 month later...

There is no standard for a competition gun except the average distance you shoot the most.

For IDPA, the max is 35 yards and the average is more like 15 so a 15 or 20 yard 0 is usually plenty.

In USPSA the average is still under 25 even though there are frequently shots out to 40 so 15 or 20 yards is good there too.

I usually zero mine for 17 (from a bag) because that is the furthest my eyes are still super accurate on iron sights anymore.

 

But to the original question... no bullets do not fly in a straight line but the deviation from a straight line is not very pronounced with good ammunition in a handgun with a good barrel at less than 50 yards. If you are shooting a magnum caliber using magnified optics off a bag, I have not seen much deviation at 100 yards with good ammunition.

This all leads me to believe the normal inaccuracies most see in a quality handgun with quality ammo is 100% user error.  

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