If your round Underwood bolts have a hole in the bottom of then for oil and or draining, then they are post war replacements. Underwood had a contract for replacement round bolts about 1948 and 1949 time frame.
If your round Underwood bolts have a hole in the bottom of then for oil and or draining, then they are post war replacements. Underwood had a contract for replacement round bolts about 1948 and 1949 time frame.