Because some states require test firing of newly manufactured guns before they can be legally sold (Mass. for one). It's nothing more than a simple proof of function. Regardless of what the "tin-foil hat mafia" wants you to believe. No state pays to have an electron microscope record bullet markings to be put into some secret file archive or database.
There is no "gun control" amendment.
No, of course not. But a gun can be a solution to some problems.
Black Powder.
It's not the Declaration you look to in order to find your gun rights. The Constitution's Second Amendment is where our gun rights in America are derived from.
john smith had the gun powder injury in 1609.
Sometimes yes, but not always.
Your question is ambiguous, assuming by capsule you mean the shell casing then this is also not the case in every weapon. Shell casings are ejected when the weapon is fired if it is an automatic or semi-automatic weapon. Revolvers, for instance, do not eject the spent cartridges.
"They could match extractor marks on the shell, yes." If they don't have the gun and it's registered: Highly unlikely, unless it being registered they also get a spent shell casing with the extractor marks and firing pin indent on the firing cap. Also, if you don't "police" your brass, they have the shell casings at the scene, where there is likely a casing with your finger prints (loading the firearm) and possibly DNA (sweat or blood on the casing). Realistically though, if it's a standard shotgun, smooth bore barrel, and you shoot rifled slugs or buckshot and leave no evidence of the shell casings behind, they would have a hard time matching it to just the projectile part of it.
When the gun is fired the shell casing is ejected by the blow-back gas and the next bullet is automatically loaded. All in one motion. The next bullet is now ready to fire.
The usual reason for this is because the casing usually ejects to the right. If you held the gun on your left shoulder, it would eject the spent cartridge (possibly) directly into your face or arm. Those spent shells can be rather hot......
Gun Powder, a shell casing (usually cardboard, cotton, and other various paper products) and an element, when burned, gives off a specific color.
Yes.
All Bolt action rifles work the same. When you fire you have to manually operate the Bolt to eject the shell casing and load the next shot. This must be done for each shot until the rifle is empty. In the case of Air soft there is no Shell casing, but it's the same action to load and fire.
Shell-ejecting airsoft guns tend to eject their shells using a spring loaded system. once the bolt, or slide is drawn back after firing, the spring will force the spent shell out of the gun
To help keep foreign matter (dirt) out of the action when the weapon is not firing.
They didn't. Modern cartridges or "bullets" still contain gunpowder inside the shell casing. The first gun powder integrated cartridge was invented in 1808, but it didn't really catch on until around the time of the American Civil War.
The extractor removes the spent shell after the gun has fired. I am sure most people think of the extractor as part of a gun. That may well be true. Keep in mind that the extractor also could be a man. In that case the extractor would be part of a gun crew.