I'd prefer the 1760 barrel due to it being rigid like the 760. Wouldn't use the soda straw barrels, ever, if you don't have to.
If you have a large enough drill, Rob, you can turn down the end using files. To keep the barrel from flopping around due to gyroscopic torque, use a bearing close to the working end (7/16" I.D. by 1" O.D.) and lock the bearing down in some wood blocks. Hold dril with one hand and files with the other. Pauper lathe!
"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."