the problem is the ME rating of the factory is just your total percentage towards the max provided by your extensions <IE, 60%> and not the actual number that is applied to the manufacturing run.  so if your ME shows as 50% what that means is you have 30% bonus efficiency to apply to the cycle.  I wasn't sure if your calculation was taking that into effect.  <this is also the reason why each lvl of efficiency seems to raise your ME by 3% instead of 2%>