i use my $140 (maybe less) Vaporite vaporizer with the whip at 310-320 degrees, .2-.3 of bud gives me at least 10-15 pulls of tasty head rushing vapor...then it starts to smell like burnt popcorn when its finished and turns a dark brown color..usually just throw it away
Thats probably too low of a temp for cannabis. Depending on the source, THC is said to boil/vaporize at about 320 or 365 which means if your vaporizer is hitting 320 its barely heating the cannabis up enough.
According to a wiki page you need to have a vaporizer set as high as about 415 degrees in order to get the 3 main Cannabinoids THC, CBN, and CBD. I run my volcano at about 395 (volcano 7) most of the time which would handle .2g of cannabis in 3 bags tops, but now I'm testing out 374 (volcano 6) and finding that it can take 4-5 bags but is less harsh and still seems to get all the goodies out (if I do 4-5 bags at 6 and then a 7 bag it will have nothing in it).
Just to see what I get from going 320 like you I'm going to set it to 3.5 and see where that goes. But I'm pretty sure the first time I got the volcano I set it to 3 or 4 and barely got anything at all.
PS: So you are using a chamber/whip vaporizer and not a fan/airpump vaporizer? That could make the difference because if the herb is heated by metal contact and air suction and not just hot air (like a volcano and others) then the herb could get hotter and even a bit more burnt which would make up for the lower temp. *Even my iolite portable handheld vaporizer is auto set to maintain 365 I believe which they said is best for cannabis