It seems that major test makers like the SAT for some reason don't allow mechanical pencils. I have always taken my SAT and SAT II Subject Tests using Mechanical Pencils even when they say not to because it seems to work. Is there a reason why they don't allow them? I use 0.5 lead and it works fine. I plan to use them on the ACT as well. Could this test give me a problem with mechanical pencils when none of the SAT's have?