Unfortunately, I can not give a good reference but here is a procedure I have read about that may solve your longevity problem.
  1. Put an "O" ring around the case just above the rim for the first firing. This makes sure that there is no gap between the bolt head and case; therefore, no stretching. The shoulder moves up.
  2. Segregate used cases by rifle. Removes problems with different head spaces and chamber depth from the equation.
  3. Then neck size. These custom made cases, for the rifle, now effectively head space on the shoulder like rimless cases and last a long time.
I was going to try this, but then started firing my SMLE's less frequently.