It's not a squirtgun, it's a water emitter. I actually had a phaser squirtgun when I was a kid. It looked a lot like the phaser in the Exploration Set model kit.
The only real difference I'm seeing is that they shifted the "tombstones" on the grip downward... note the gap at the top of the grip and how they go right to the bottom of the handle. Like a 2nd-3rd season dummy phaser.