Look up on the Web under "Air Gun Repair" and find a shop closest to you.
If you don't want to spend any money on repairing and you want to repair it yourself, you can just take the gun apart, find whats causing the trouble, and decide what needs to be fixed or replaced. My stinger p36 handgun would load the bb in the chamber then get stuck... so i took it apart and then found out that my gun has been damaged when i dropped it. that the easiest way!
A pellet gun is not adequate for protection, and will get you arrested.
It is a pellet pistol and yes.
Is this a Pellet, BB or airgun? If it's a pellet or BB gun you can use a .177 cleaning rod down the barrel to push the Pellet back out of the barrel into the breech. Make sure the pistol is not cocked. I suggest you look up "air gun repair" on the web and take it to someone who repairs airguns to have it fixed.
They are about the same, depending on the pistol. C02 has a tendency to be a little louder on certain pistols but not much difference.
Please state the condition of the pistol to get an estimate of value.
The Crosman model 150 was made between 1954-1967. It is a .22 cal pellet pistol.
It will shoot pellets or bb's. They normally use an air cartridge.
It can be either a BB gun or pellet gun. The slide, on top, blows back and reloads the next shot when you fire the pistol.
If you want an estimate of value then you will have to state the model and the condition of the pistol.
This pistol has not been made since 1941. Your best bet is the web, someone like gun brokers or guns America.
I think you need to rephrase your question. Do you mean Firearm, Air soft, BB gun, Pellet gun or Paintball. It also depends on where you live.
I assume you mean "In current or recent production" My guess, for a BB gun, would be the Walther PPK/s. It's 6.1" For a pellet pistol, there are too many that are the same size to list here. But most start around 7.1 plus inches in length.