I was able to, but not when I was recording it, I saw your reply today and tried a few times. (I dont have more time to do this today, sorry.)
If you open the weapon selection wheel while picking a weapon up the weapon sprite changes to the hand-held version.
This can happen because you slide a little bit after you stop moving. Maybe also if you open it the same frame you collect the weapon, I'm not sure.
If you switch weapons exactly when you pick another weapon up, the weapon starts firing the wrong projectiles.
When I found this I switched from the chaingun to the shotgun when picking the plasma gun up.