Are you working from a refence image? The stock looks a little out of proportion and you could divide some of the heighten areas better. I know its a wip and it's early in the progress so It's hard to give much criique yet. You do appear to have a problem in the barrel though, as some faces aren't appearing?

Link of M90 references just in case:
https://world.guns.ru/smg/fn_p90_parts.jpg
https://www.civil-defence.org/product...rearms/p90.jpg
https://www.airsoftplayers.com/p90/images/P90.jpg
https://neuroshima.valkiria.net/img/p90.jpg
https://www.arniesairsoft.co.uk/news/...-tac-sling.jpg

Good luck and happy modeling.