Props get stuck mid air, when moved with the physgun

What steps will reproduce the problem?
1. Spawn any sbmp prop
2. Use the physgun to move it.

What should happen? What actually happens?
Well I thought the prop was supposed to move through the air without any 
troubles.
But it doesn't :( It moves a tiny bit and then it gets 'caught' in mid air and 
you have to let go of it to try again. Also when you do let go of the prop in 
mid air it floats down to the ground too slow, well slower than i remember it. 
This seems to be a new problem.

What version are you using (if SVN give revision number)?
SVN 1370

Please provide any additional information below.
I have just started using the mod after a period of not using it... so there 
have been a lot of updates to both the model pack and gmod. I dont know which 
is at fault here.

Original issue reported on code.google.com by james.sh...@gmail.com on 21 Nov 2010 at 10:55

code-google-com / spacebuildmodelpack

Props get stuck mid air, when moved with the physgun #67