no
No, the bullet will not seat.
how far does a 50 caliber sniper rifle shoot accuratly
No.
No.
You can from some, but they have to be designed to shoot both.
No
Although there are many variations, most AK47 shoot a ~30 caliber bullet (7.62mm).
No, it won't fit. The .45 caliber bullet is 0.45" in diameter; the .30 caliber bullet is .15" smaller. The brass is different size too.
Yes
100000000 meters
No, you cannot safely shoot a .45 caliber bullet from a .40 caliber handgun. The .40 caliber handgun is designed specifically for .40 S&W ammunition, which has a different casing size and bullet diameter compared to the .45 caliber. Attempting to use .45 caliber ammunition in a .40 caliber firearm could lead to dangerous malfunctions or serious injury. Always use the correct ammunition specified for your handgun.
No. A smaller caliber will either not fire at all, or will split the cartridge casing if it does fire.