New WInchester 1892 Short disassembly?

[41 Colt]

I want to add a sling mount to the magazine tube in front of the foregrip and need to pull out the tube. I removed a roll pin in a front bracket, the end cap screw and even to screws that seem to just hold the foregrip tip inplace and the tube would not budge.

Anyone know how to remove it?

This is the gun:

http://www.winchesterguns.com/products/catalog/detail.asp?mid=534162