Looks like a cannon for a ship - which means there would be a lot of other details around. It seems like you could do it with fewer polygons - like don't worry so much about round wheels, and a round cannon barrel (since there might be a dozen cannons on a deck).

You can fake the look of roundness with textures. I did a 19th century field cannon in my set (see link in my signature -- field cannon), and the cannon is actually really blocky, but I used a detailed texture (still only 256x256).

Anyway, that's my two cents - any my shameless self-promotion of my models for sale.