The chambers on Lee Enfields were cut somewhat generously. The theory was that the gun would feed and shoot even when dirty.
That's not a problem because the case headspaces on the rim, but it does become a concern during reloading as full-length resizing can dramatically shorten case life.
If you neck size only, you'll increase your case life quite a bit.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.