You can cancel the stun animation from stun grenades...

Only found this out by mistake but apparently you can immediately cancel the stun grenade animation and ADS restriction, simply by double tapping switch weapon to put you back in your original state. 

Haven't tested it since and maybe people already knew? Seems like gameplay flaw so I thought I'd report it... not sure if it's actually worth reporting.

Unfortunately, I don't have the clip ( sorry), I'll try to get one if I can or maybe someone else could test this?

Regards,