Dry firing is fine.
Maybe the pump isn't forward and in battery, you can easily just disassemble the whole thing to find where it's hanging up.
While empty, you can rack the action like you'd be loading, and the action lock pops out and you can squeeze the trigger. After squeezing the trigger, the action lock depresses back into the trigger group and you can cycle the action again. Looking at yours, should just be able to cycle the action.