1. The oiler is correct, but an empty .30-'06 case will do the job just fine, as many WWII vets knew. (I don't think anybody ever actually used the %%#$ oiler.)
2. The army, in its wisdom, spec'd the stock to just allow room for the oiler and the old WWII thin sling. Then they adopted a thicker sling. You can fight it, or do what I did as an armorer - get a flat file and take off a little wood on the front inside of the cut.
Jim