First boil some water.
Get a long cardboard box that will fit the stock. Line it with polyethyline, trash bags, painter's drop, whatever will hold boiling water. I used some thick poly I had around for the garden.
1. Put on plastic gloves.
2. Cover stock with Easy Off Oven cleaner (the NO LYE kind).
3. Scrub with nylon brush.
4. Pour boiling water on stock.
5. Put kettle back on.
6. Repeat until 2. -- 5. until stock is covered (I had to weigh mine down, but we have regular water here, pretty much).
Let sit for thirty minutes. Don't let kettle go dry. Scrub again. Rinse with clean boiling water. Wipe with towel.
Repeat again tomorrow.
Let dry for a week before oiling or sealing.
Good luck. I think 1903's are straight BLO. Try asking at
www.jouster.com
1903 forum.
Regards.