its a break barrel so through the chamber feed hole just put the bullet in and close it up and your ready to shoot
You will have to contact the maker to find out.
Gamo never made a Sniper model rifle. It depends on the model, each one is different. You need to locate the model number and ask your question again.
No they won't fit. If you force it, it will ruin the rifle.
Currently Gamo makes an "Air Shotgun" that fires both shot or a .22 cal Pellet. It's the Viper Shadow Express.
It might fit, but why would you want to do that. It has no gun powder and won't fire.
ask a gunsmith for help
Gamo Viper Air Shotgun it shoots a .22 cal pellet but also converts to a special Shotshell see: see the related link
This is a very nice air rifle. It is a .22 caliber not a .177 caliber rifle. it was made in two variations from 1957-1964. See the link below for the Owners manual.
Ask a gunsmith for assistance.
put it in the magazine one at a time
Yes
There are several good rifles for hunting rabbits. Crosman, Gamo, Beeman and a dozen other air rifle companies make excellent choices for hunting rabbits. But expect to pay about $150 starting range for a hunting rifle. The lower priced rifles are just for plinking and are not that accurate over a long distance. Purchase a rifle that has rifling in the barrel. Do not get one that is smooth bore like a BB rifle. In fact do not purchase anything that shoots BB and pellets. They are fun but not what you want. Also lean toward the .22 caliber rifles they may be slower in speed than the .177 caliber pellets but they have more knockdown power. This is what you want. I have shot rabbits with a .177 pellet and it just went through them at times and they hopped away and died later. A .22 pellet will take them off their feet. Your choice of pellets is also important. I suggest hollow point pellets by Crosman, Gamo, or Beeman. They deform when they hit a target and will take them out easily and humanely One air rifle I would take a good look at it the "GAMO VIPER air Shotgun" See: ( http://www.pyramydair.com/p/gamo-viper-break-barrel-shotgun.shtml ) it gives you the choice of a .22 caliber pellet or a special air Shotshell. It has plenty of penetration and give you a better chance of getting the target. Do not try to hunt with a BB rifle it just won't work.