THE ANGLE. We often talk about various snuff-techniques, and how hard to sniff/snuff, etc. But, I think the "angle" of intake is a big part of why various snuff-taking techniques work for some and don't work for others. Two people can do a technique exactly the same (apparently), but placement of your nose and head angles the snuff up your nose differently. You want the snuff to land on something BEFORE it hits the deep part of the sinuses and the back of your throat. So, if you try a technique, and it doesn't work for you...position things differently so that the angle of intake is different and see if that helps.
Even if you are snuffing off a spoon, where you place the spoon in relation to your nostril changed the angle of intake. If you place the spoon right dead center in your nostril hole, the snuff is going straight up. If its a course snuff, this might be fine. But, a finer snuff is going to sneak right back into your deep sinuses and throat. If you place the spoon to the side of the hole and back off a little, the snuff is going to angle in on the sides of your nostril, and not make it back so far.
Same theory on where you hold your pinch, your bullet, your boxcar, or how you descend down only a pile on the back of your hand.