[saxman]

A good question that I hoped would be asked. Basically, boiled linseed oil is a surface finish for wood which can result in a lustrous to glossy finish. Think of it almost as a varnish which dries after application. This or tung oil would be good to use if you desire a glossy finish.
Raw linseed oil is applied to military gun stocks to season and protect the wood without leaving a glossy finish, which would obviously be detrimental to any military application. Since the Luger is a military weapon, I personally prefer to use raw linseed oil to treat the stocks. Raw linseed oil is not meant to be painted on like varnish - it is rubbed on with a cloth in a light coat and allowed to penetrate the wood. When wood stocks were on G.I. weapons, this was the procedure as the last step in cleaning and oiling the weapon. Boiled linseed oil and tung oil are recommended by those who prefer glossy grips. Even raw linseed oil will give a sheen over time as the wood is handled and rubbed. U.S. G.I. stocks had to be periodically cleaned, sanded, stained and re-oiled to be returned to their correct appearance. This was usually done when the weapon came in for Depot maintenace. Anytime you see a Carbine or Garand with a glossy stock, you know that stock is not in original configuration.
So, bottom line, if you want glossy stocks use boiled linseed oil. If you want the flat military look, use raw.
Important note: Any linseed oil is capable of spontaneous combustion, particularly on paper or cloth. This material must be disposed of properly to prevent fires. One method is to keep rags, cloth, etc. in an airtight steel container until disposal. Ask your local Fire Dep't. for more particulars.