For Experienced Shooters?

no. the bore line is the same relative to the stock. the sights are set for a specific distance so that the trajectory line crosses the target at the correct spot for a hit.

Gravity is working on the bullet from the second it clears the barrel whether the arm is upside down or not. The rifling in the barrel causes the bullet to spin and stabilize for straight and true flight (Like a spiralling football-That is why a football is pointed). That straight flight will remain and the gravity will remain until the projectile hits a object or falls to earth, regardless of the arm position it was fired from. I do not recommend a field hunting position of firing while standing on your head. The ammo tends to fall to the ground before you can load the magazine or close the bolt! Maybe this would be a way to lengthen the season for rifle hunters? Start doing your pushups now for next season :) Hey, maybe a scope mounted on the bottom of the stock so you don't need to stand on your head?

The bullet will drop, no matter how the rifle is pointed. If it's pointed upwards, it won't drop imediately, but as soon as it's out of the muzzle it's going to stop rising fairly rapidly, then drop. If it was upside down, you'd have the bullet drop through your line of sight fairly quickly, then continue dropping.

It's the same physics as anything else. If you have a straw, and you shoot a spitwad out of it, it's going to fall straight down. If you turn it in any other direction, the trajectory relative to gravity remains virtually unchanged. The same is true of guns, sights are usually aligned to cross the flight path of the bullet in two locations, after which the bullet will continue to drop towards gravity.

If the rifle is held properly , the sight is such that the bullet rises above the line of sight , then as gravity acts on the bullet , it falls back into the line of sight . If the sight is set properly for the distance , the bullet should hit the target .

If the rifle is held upside down the bullet immediately begins to fall because of gravity . The barrel is now pointing downward from the line of sight , so the bullet will fall far short of the target .

Even when the rifle is canted ( leaning to one side ) , the entire idea of sighting is lost . The bullet will not curve to compensate for the cant . It drops straight down .

If the line of bore was parallel to gravity, you could rotate it 360 degrees, and it would shoot the same....If you are using the line of sight, however, it would be different....The sights are used to set the angle of the bore "above" the line of sight, and the velocity loss and gravity will bring the bullet back to the line of sight....If the rifle was rotated 180 degrees, or "upside down", the bore would be angled down to the line of sight, and once it crossed the line of sight, it would never return to the line of sight...Draw it out on a piece of paper, and then turn the paper 180 degrees....At close range, it may be negligible, but at longer range, once the bullet started down, it would continue down, with gravity......

The arc of the bullet is obviously going to be the same. If you're standing on your head to aim, (1) I want to see that, but from well behind the firing line, and (2) you have to consider the change in parallax with your sight picture.

Gravity is what causes the bullet to "arc" while it is in flight. It doesn't matter if you hold it upside down, sideways, or correctly, gravity will affect the bullet the same way.

no the trajectory it not affected buy angle of the rifle but more by gravity so for instance you shot a gun in space it would go up up up and not come back down thats why a heaver bullet drops faster

The bullet does not arc, it just appears to as it relates to the line of site of the sites. It goes out straight and then drops. However since the sites are above the trajectory of the bullet as it leaves the barrel, it appears to arc, but that is just as it relates to the sites. So if you turn the gun upside down it will have no effect on the bullets travel.

If you "turn the gun upside down" you don't

invert the bullets path.

It will cross the line of sight once, and keep falling (up?).