Gun shops, gun shows, Numrich, Brownell's, MidWay USA, etc..
No. Iron sights or peep sights (aka aperature sights) are the only type allowed for the merit badge.
Pretty much the same as any other military rifle sights, except for the ones with anti-aircraft sights. These folded OUT to the sides of the rear sights. The idea was to permit a rifle to fire ahead of an aircraft, which would allow the airplane to fly into where the bullet was headed.
Meters
Receiver, stock, barrel, sights
telescopic aperture battle
This refers to adjusting the sights on a rifle for elevation (up/down) and windage )left/right) so that the sights are pointed to the place that the bullet strikes at a given distance.
900 meters, depending on the rifle, sights, and skill of the user.
Things that glow in the dark like some rifle sights and military lensatic compasses contain tritium.
gun shop, gun show, pawn shop, want ads, Shotgun News.
About 300 meters, depending on the rifle, sights, ammo, and skill of the shooter.
You should really leave this to a gunsmith.
$100-$200, if you have an excellent condition rifle, complete with all sights.