Hi, I'm new to shooting and I wanna know which shotgun will be right for me :) Ima get it this weekend or next hehe
what's the difference btwn 3" and 3.5" chamber?
Those are magnum loads used for hunting primarily. I don't know of common use in skeet. A barrel chambered in 3" will shoot 2 3/4" shells and should do all you want it to.
What's the difference btwn 18", 24", 26" and 28" barrel?
Barrel length contributes to the ease of a swing, with a shorter barrel generally being easier to start in motion, think inertia: less mass, easier to start, more mass easier to maintain, i.e. helps with swing and follow through.
what is tactical?
Tactical is used in defensive or offensive threat mitigation. Usually unobtrusive finish, like matte black, or even various camo patterns. Higher magazine capacity, shorter barrel to facilitate use in close quarters (CQB= close quarters battle). Rails for optics or lights, optics or ghost ring sights.
What is H2O?
That is a model of Benneli shotgun. Made of wet atmosphere with stainless construction. Special purpose.
Impact Guns - Benelli Nova H2O Pump 12g 18.5" Nickel
Should I get the Benelli Nova, Benelli Super Nova, Benelli M1, Remington 870 Express, or Mossberg 500?
Get what you can afford. Whichever model you can get to fit, or make fit. Skeet shooting at a high level requires a well fitted shotgun, perhaps even customizing the stock to get the right fit. Length of pull, simply put, the length of the rear stock is absolutely going to be a difficult problem for you to solve with your small size. I would suggest a shorter barrel, like a 26" would be easy for you to handle. Have you considered a double? Might be just the ticket for you, although possibly more expensive. Most shotguns are sold now with removeable choke tubes, look for that feature to tailor the gun to the conditions. Good luck.
P.S. I will only do skeet/trap shooting.. prolly weekly. I'm not shooting any animal cuz I love animals @.@