Are the brown main shells thicker than the greens, apologies I am still struggling to understand the difference thickness of them all.
Ted - you might have been on to something about the grease, I did them again yesterday without grease and on the original shells got 0.038mm this time and the new green shells I got to try was in between 0.038 and 0.050mm. having said that I am still not convinced its not me buggering it up, but its a learning curve.
On a positive note the big end shells where all bang on 0.038mm so I don't need to replace them.