John,

The drain holes will work, I'd also remove the top front bead to allow air/fluid to escape when you submerge the barrels. I would be VERY aggressive! I'd use the baking soda to neutralize the caustic soda/lye and I'd not be afraid of a gentle boil with this solution, further several boilings with plain tap water to finish off, then spray oil in the weep holes. Lots of oil! 3in1 will work better is Brownell's water dispalcing oil, even kerosene to remove the water. Good luck. DR. BILL