sighting in for different positions of shooting?
#11
Join Date: Mar 2005
Location: old pa mountain hunter
Posts: 382
RE: sighting in for different positions of shooting?
CZ2506 i don't really know how to break the news to you but every bullet, from every gun, ever made starts to drop the very instant if leaves the barrel. and believe it or not your point of impact will be slightly higher shooting down hill.
#14
RE: sighting in for different positions of shooting?
and the downhill, siting to standing isnt a great enough of a drop to effect the bullet unless it is an extremely long shot. Or atleast thats what i have always been told. you have to have a nice downhill shot for any given effect
#15
Fork Horn
Join Date: Mar 2005
Posts: 287
RE: sighting in for different positions of shooting?
MA maybe you should start reading something other than Guns & Ammo for a change. Like a physics textbook. If your line of sight down a scope is level the bullet leaving the barrel has to rise to intersect the line of sight. Since the air pressure on all surfaces of the bullet are equal, this upward movement against gravity is caused by thrust. The bullet continues to overcome the force of gravity until it reaches the apex of its trajectory (the highest point above line of sight). At this point gravity starts to pull the bullet down.
If you're shooting at an angle where the the barrel is level and the scope is pointed downhill the bullet starts to fall as soon as it leaves the barrel. When a bullet starts to drop, gravity pulls it down at a constant rate of 32 ft/ sec^2 whether it's at the muzzle or the apex of the trajectory. Since a bullet fired downhill or level won't have traveled the distance to the apex of a bullet fired uphill, it will will hit the ground after less time. That's why you need to holdover on a downhill shot.
Clear as mud?
If you're shooting at an angle where the the barrel is level and the scope is pointed downhill the bullet starts to fall as soon as it leaves the barrel. When a bullet starts to drop, gravity pulls it down at a constant rate of 32 ft/ sec^2 whether it's at the muzzle or the apex of the trajectory. Since a bullet fired downhill or level won't have traveled the distance to the apex of a bullet fired uphill, it will will hit the ground after less time. That's why you need to holdover on a downhill shot.
Clear as mud?
#16
RE: sighting in for different positions of shooting?
crystal =) use this http://hyperphysics.phy-astr.gsu.edu/hbase/grav.html
#17
Join Date: Mar 2005
Location: old pa mountain hunter
Posts: 382
RE: sighting in for different positions of shooting?
CZ2506 YOU ARE STARTING TO MAKE YOURSELF LOOK SILLY. YOU DON"T HAVE THE SLIGHTEST IDEA WHAT YOU ARE TALKING ABOUT. HERE IS A GOOD PLACE TO USE THIS LINE AND IT GOES LIKE THIS. DO YOU REALLY UNDERSTAND EVERYTHING YOU KNOW.[:'(]
#18
Join Date: Mar 2005
Location: old pa mountain hunter
Posts: 382
RE: sighting in for different positions of shooting?
CZ2506 nothing personal but you set yourself up on this one. here's an example. i'm driving down the road in my truck. using the gas pedal for thrust as you call it. i got equal pressure on all sides. how come my truck didn't float off into space. and yes i do like to read guns and ammo but not for silly things like this. maybe you should pick up a copy. man i can't wait to tell the guys about this one.
#19
RE: sighting in for different positions of shooting?
Roscoe,
I found out about the sling changin' the point of impact in the most embarrisin' way. I was visitin' my Dad after about a 7 year absense, he took me pasture griz huntin' with his new Mossberg Chuckster. I carried the rifle and he carried the glasses. As hog huntin' goes he spotted one when we were in the middle of a hay field, and it was in the adjoinin' one. It was about a 150 yard shot so I sat down and got into the sling. He said "You can't shoot from out here lets get up ti the fence and rest the rifle". Now I'd only been huntin' Caribou twice and elk 4 times since the last time I saw him. Not to mention speed goats and mulies in open country. To make a long story short I fired about 5 times and he kept sayin' "Low". Finally I emptied the clip, and we walked over to the chuck which humped up on the second shot. It was pretty sick so he stomped it's head and threw in into the hole. Then he took me to his rest, where I shot a 1.5 group at 100 yards. Then I got into the sling, and shot three shots into an even nicer inch, but all about 6 inches low. []
I found out about the sling changin' the point of impact in the most embarrisin' way. I was visitin' my Dad after about a 7 year absense, he took me pasture griz huntin' with his new Mossberg Chuckster. I carried the rifle and he carried the glasses. As hog huntin' goes he spotted one when we were in the middle of a hay field, and it was in the adjoinin' one. It was about a 150 yard shot so I sat down and got into the sling. He said "You can't shoot from out here lets get up ti the fence and rest the rifle". Now I'd only been huntin' Caribou twice and elk 4 times since the last time I saw him. Not to mention speed goats and mulies in open country. To make a long story short I fired about 5 times and he kept sayin' "Low". Finally I emptied the clip, and we walked over to the chuck which humped up on the second shot. It was pretty sick so he stomped it's head and threw in into the hole. Then he took me to his rest, where I shot a 1.5 group at 100 yards. Then I got into the sling, and shot three shots into an even nicer inch, but all about 6 inches low. []
#20
RE: sighting in for different positions of shooting?
CZ2506- you are completely wrong.
Shooting uphill or downhill will raise your point of impact not lower it, IE if you are shooting uphill or downhill, your rifle will shoot high.
Scopes, irons etc....
If the scope is adjusted so its parallex free- most hunting scopes are supposed to be free of prrallex at 100 yards and beyond, it shouldn't matter how you hold the rifle. Unfortunately, on alot of scopes, you have to go a ways beyond 100 yards before parallex disappears. Rimfire scopes often have an adjustable objective lens so that the scope can be adjusted free of parallex at ranges short of 100 yards.
With iron sights, it matters a lot how you position yourself behind the rifle. For shooting a rifle from a bench with iron sights I lock my cheekbone against the back of my right thumb to get a consistant cheekweld. When shooting highpower matches, I usually have to adjust my sights down about 2 minutes when shooting from a sitting position as my eyes are much higher up on the rifle than if I'm shooting prone or standing. If I were gumby and had unlimited flexibility in my neck and back I would be able to get the same cheekweld as with standing, but I'm not, and most people aren't as well.
A way of looking at open sights is thinking about shooting a bow with a peep sight. In order to get comnsistant groupings, the eye, and sights need to be on the same plane every time. How archers do this is by using the same anchoring point every time. If an archer were to anchor on their earlobe with one shot, then on their chin or cheek the next, even with a peep sight, the shots will not be consistant.
Shooting uphill or downhill will raise your point of impact not lower it, IE if you are shooting uphill or downhill, your rifle will shoot high.
Scopes, irons etc....
If the scope is adjusted so its parallex free- most hunting scopes are supposed to be free of prrallex at 100 yards and beyond, it shouldn't matter how you hold the rifle. Unfortunately, on alot of scopes, you have to go a ways beyond 100 yards before parallex disappears. Rimfire scopes often have an adjustable objective lens so that the scope can be adjusted free of parallex at ranges short of 100 yards.
With iron sights, it matters a lot how you position yourself behind the rifle. For shooting a rifle from a bench with iron sights I lock my cheekbone against the back of my right thumb to get a consistant cheekweld. When shooting highpower matches, I usually have to adjust my sights down about 2 minutes when shooting from a sitting position as my eyes are much higher up on the rifle than if I'm shooting prone or standing. If I were gumby and had unlimited flexibility in my neck and back I would be able to get the same cheekweld as with standing, but I'm not, and most people aren't as well.
A way of looking at open sights is thinking about shooting a bow with a peep sight. In order to get comnsistant groupings, the eye, and sights need to be on the same plane every time. How archers do this is by using the same anchoring point every time. If an archer were to anchor on their earlobe with one shot, then on their chin or cheek the next, even with a peep sight, the shots will not be consistant.