As I gather from vintage specifications for SMLE manufacture, the finished woodwork, awaiting fitting was STORED in drums of raw linseed oil, often for months. And this was after the raw flitches had been air dried for YEARS.
The only way you would get more linseed into the furniture is with a vacuum tank. In these, the "article" is sealed in the tank, the air pumped out and the vacuum held for a specified period,
Then, the linseed oil is let in. Because most of the moisture / oil etc in the wood has been drawn out via the vacuum pump, the new oil penetrates quite deeply.
You can substitute epoxy or polyester resins for the linseed and end up with a wood-fibre reinforced plastic stock that still looks like wood but is so rigid it will almost ring when struck. It will also be VERY resistant to dents, rot, borers and warping in the rain. NOT a cheap option, but do-able.