Pharmacology - how much is a blocking dose of methadone?

[jmunny fo twunny]

i am sorry if this has already been answered, i searched the forum and couldnt find anything but i have been told that methadone does not block your opioid receptors yet some people say it does. swim goes to the methadone clinic everyday and is up to 140mg and has noticed that large amounts of herion used interveniously (.5g in one shot) does not have any effect on them at all. where as the same amount would get swim to a nice warm place but now they dont even get a rush... and someone at the same clinic is on 180mg and claims that they still get high off a smaller amount of diesel. i know everyones body is different, it just doesnt make sense to me. could anyone help swim out?