I am not really impressed with the lack of detail and time spent on this creation, Although it resembles some features of what I think you're implying that is the Barrett M82A1 Sniper rifle.
The lack of detail was because I had to draw it by hand as I do not have transparent windows. I spent most of the time on the electronic system that controls the ammunition.
@PowerShroomsAttack I did but it is rather difficult to copy an image on ms paint to powdertoy while making sure that it does not self-destruct or reduce the effectiveness of the weapon.