Stan, I do not put any oil on the plug. The only oil that is there is a light coat from storage. On the 10 ga. the plug was .773 and the bores were .750. I have made aluminum plugs for 10, 12, and 16 gauges as a go/no go fit.
[Linked Image from i.imgur.com]
These naturally are for 12 ga. The smallest at .724 is for some 12 gauge L.C. Smith hammer guns that have a smaller bore. Have never run across an L.C. Smith hammerless that small in diameter.

Thanks Mike, I use Imgur as a photo hosting site and when I want to post a picture I click on BBCode and click on copy. Most times it works great.

Also wanted to mention Happy Thanksgiving to all.