that's an HK MP5 or similar. sniper rifle's are coloquialistically presented with a scope and a much, much shorter magazine. the magazine will also be thicker, because the rounds themselves are longer, not because the slug is substantially larger than similar calibers, but because they use more gunpowder.
also: i have no idea what this work is communicating, but given gottfried's talent, it's certainly my failing and not his.
I'd love to see your work in person, but I don't think I'll be able to travel far to see it anytime soon. Is there anything I could do to help it be brought to either Portland, OR, or Seattle, WA? I don't know much about how the art world operates at your level but if you have some ideas about how I might be able to help make it happen please let me know.