BFT Sub removal - any tips??

[acmoh2024]

Hi all, 

I'm struggling to get a BFT Sub out of an FCS box. 

Does anyone have any tips for getting these out? Are they know to rust onto the gate hub when in the ground for a long time making separation difficult? 

Grub screw has been loosened but no amount of movement enables it to come out, so any thoughts would be helpful. 

Thanks