Great tip, Hambone.
I use a plug cutter to make the dowel. A ready made dowel has the grain running along the length. By cutting the plug out of the face of a piece of stock, the grain runs in a direction that provides cross grain for the screw threads. Tear out is much less of a problem when threaded cross grain.
Another problem with dowels is incosistency in the diameters. The dowels that are available at the DIY stores are often off as much as 1/32".
For actual doweling purposes I make my own. I have a piece of 3"channel iron with holes drilled through it that corr- esponds with the dowel diameter. If I need a 1/4" dowel I rough out a blank around 5/16" and just drive it through the 1/4" hole. They come through the hole perfectly round exactly the size of the hole.
I realize that the last paragraph has nothing to do with the original question but I thought that you, as a woodworker, might find it of interest.
The glue groove that you pointed out is excellent advice. If the plug fits as it should there is very little space left for the glue.
Pkr2