Parts of it look okay, but honestly, you need to spend a lot more time on these models.
It looks really rushed and thrown together, try spending some time on it to make it something respectable.
This is better than your prior models with their haphazard random-polygon sides, but it still needs a lot of work.
The entire back side of it is really just nonsensical; nonfunctional as an SMG because it is too long, but it isn't shaped right to be a stock.
Also, why are there iron sights and an action sight? The action sight blocks the iron sights.
Overall, it needs a lot of reworking. Try looking at professional models, or even pictures of real rifles to try and form it.