Okay, there is no delicate way to put this ... (well, there probably is) ... make SURE that your bowels are empty. I mean EMPTY. Don't just take a dump, douche.
I'm a bottom, and can take pretty much anything, and while I know that everyone is different, the logistics of the intestinal tract says that if 10 inches is going up there, there needs to be room for it.
And I'm assuming that you are lubing the INSIDE of your hole, not just the sphincter ... and also lubing his dick.
If you still have trouble taking him ... send me his address.