OP:
First: If a point snorted got you off, sounds good/fire product, ime
Does this stuff taste fairly pure, with a tiny amount on tongue, maybe check a couple different spots in the bag? I'm just having a difficult time with the 3.5g in such a short time. Not doubting you, but a cut like MSM, it's difficult to detect. Not to cock size but an 8 ball of fire shards from Tucson in '03- '04 would last me five days, at minimum 3, if I was sharing. Smoking all day, staying up a week at a time. I always smoked (a few IVs), snorting was reserved to checking purity in absence of a kit. It just hurts too damn much.
Not perfect, but larger shards 1/4" - 1" generally - is less cut or was cut during crystallization which would cause the shards to break up with hot spots and hot cut spots.
While you switch to smoking shards (my recommendation, or parachuting), here's some basic directions from detecting common cuts to technique, plus please read the mega thread in OD, if you haven't already.
If you have an oil burner/meth pipe smoke some, like just a good solid hit maybe 1/4 of 0.3 pts, you'll need about 0.1- 0.2 minimum left over to cool, but be sure it all melts evenly over time (pretty quickly) as well, you're not smoking it all now, but more left behind helps the cut test. Let it cool with the top blocked- pencil, stick, coin, no plastic or fingers - I realize you snort, but if you keep going you'll have to get a pipe, DO NOT IV! Ruins lives like 3x as fast as smoking it...
Did water collect on the sides of the bowl? That's MSM cut, or another one. All of it should puddle at the bottom, fairly quick after heat removed and look fairy uniform, sort of looks like melted shards looking up through the bowl- don't invert the bowl...
If after cooling it's real brown and the next hit tastes like shit you over heated the first hit, next time roll the bowl back and forth about 20 - 30% while it's over flame or still hot/warm and remove heat once smoke appears. You may well know this, but in case this is your first switch to smoking properly (not off tin foil), thought I'd add that...
Take it easy, I suspect you're in deeper then you're admitting to yourself, I try not to don't judge I want to help.
Please be careful.