Questions on Paint

[RSWiser@aol.com]

Well I have been stripping the paint down to the metal.  Slow work.  I have 
gone through the following colors.
Creamy White
Gray primer
British Green (in places)
Gray primer
White (I presume the original "Moonstone")
and finally a Red Primer.  I presume this is the original primer from the 
factory since I am finding in almost entirely around the car except where 
there have been a few repairs, and even under some of the repairs.  
This red stuff is very difficult to get off.  Any tips.
Rob