front sight pin removal

Greetings,
I have a Jap Type 99 short rifle that has a lot of surface rust on the exterior. To clean it up, I need to remove the front sight. The front sight is held on the barrel by a roll pin. I have tried to drift the pin out with a hammer and punch, but it's not moving at all. I don't know if the pin has been staked in, brazed, or what. Does anyone have any suggestions on how I can get this pin out to get the front sight off the barrel?

Thanks,

Stripper Clip

Lots of penetrating oil, heat and a roll pin punch. You can try to heat it, then use a can of compressed air (key board cleaner) and spray it good. The compressed air is charged with R134 or similar refrigerant. A cold shock to the pin may break it free.