100-400 USD
Unknown.
Ruger currently makes about 8 different models of air guns / rifles. All of the current models are break barrel. All of them come in .177 caliber except 2 models that also come with a .22 caliber barrel. If you own one of the .22 caliber models then yes the .177 caliber pellets will slide down the barrel and fall out. Its too small for the barrel. Take a close look at the markings on the side of the loading chamber to see if the rifles is a .177 or a .22 caliber rifle. Lets assume you own a .177 caliber Ruger. but the pellet fall out the barrel when it is shot. In that case you most likely have a damaged air chamber inside the rifle. If you are asking what fires the pellet out of the barrel, then its the spring inside the air chamber that compresses the air ahead of it when it is fired and this air pushes the pellet out of the barrel.
Good rifle, good caliber for most uses. Did you have a specific question?
If sales falter, yes.
It will be marked on the barrel.
A call to Ruger will get you the answer.
You need a gunsmith.
50-650 usd
10-1000 USD depending on exactly what you have.
150 USD
Well, I would say in the range of $1000.Unknown caliber. Contact Ruger
They were made in several calibers- will be marked on the barrel.