I got a reply from Barnes telling me that they don't make a 300 gr tsx bullet, but said that they would place my request on the future desire list.
In the mean time I bought a box of the 300 gr X bullets. After looking the situation over I think that I can chuck up my collet attachment on the lathe and cut a couple of shallow narrow grooves like those that are on the 350 gr TSX bullets. Probably will only do 5 bullets since they are priced dearly if my idea doesn't work. Looks to me like this might be what is done on the 350 gr bullets. Any ideas or suggestions....... Don