I have a few brass moulds, both from Night Owl and MP. The "trick" for ME is to follow the "how to" instructions on NOE web-site re cleaning and first use of brass mould to a "tee"!!! -- http://noebulletmolds.com/smf/index....msg2.html#msg2 ; and, raise the temperature of your allow significantly! I "fought" with many, many wrinkled boolets after re-cleaning, re-cleaning (did I type that again?), smoking mould with a Bic lighter, etc., etc., ... when *MY* solution to get almost-perfect boolits was just to raise the heat up. 'Specially for brass moulds with pins -- at least in my wee casting experience, the pins seem to both need, and like being hot!
Good luck! I cannot determine whether the MP or NOE mould is better -- they're all from either manufacturer, imho, the best!
Good luck!
geo