I don't think the model was finished, it was probably 50-60% done. On the sight, there is no place to look down through, and no ironsight in there.
The model doesn't have enough detail to look really good, giving it a skinned and boxy look. This would be o.k. for an ultra low poly replacement, maybe for counter-strike 4 years ago. This model is similar in detail to the counter-strike m4. (i don't see it anymore tho, i have all custom models and skins)