Alex,
If you will be using a pump to fill the rifle you may want to look at rifles that fill to only 3,000 PSI. It may take forever to pump the Gladiator up. You may want to look at the Air Arms or BSA rifles. Look at Matt Dubbers video's. Check out all the reviews of the Marauder, another gun that fills to under 3000 PSI. I know you are young so you can pump, but it might take the fun out of it for you having to pump rifles with a large reservoir that fill to 3,500 PSI.