Hey Spinner, I never even try to sex mine till they are about 3 weeks old---then I usually sex them so I will be able to advertise them(pre-sell). I never had a problem sexing them at 3 weeks and older.It's easy to tell Bucks from Does on day 1, then it gets almost impossible until they are around 8 to 10 weeks, some even longer. But at 6 months it should be real obvious by feel without looking.
I never use enough pressure to "pop" out the males part. I just look at the Hole. I use little to no/gentle pressure. I am about 100% accurate at around 3 weeks of age---I never try to sex them any earlier---I have no need to know any earlier if I did---I would Check them out.The boys look like girls until you push a little harder and get their little package to pop out further.