If you neck size the body will expand to the point it needs full length resized every so often. I full length everything in 303 and 30-06 because I want to be able to shoot it out of all my L.Es and American Mil Surps, so no direct advise. On others I have singles (example 1918 Carl Gustav 6.5 X 55) I full length resize every fourth firing. Others might be able to tell you what they are doing in 303 and 30-06. A chamber gauge could be used but in military 303 bores I've been told it's hit or miss due to bore size differences. Good luck.