Every Time...

[Curly Cut]

i've noticed this exclusively with "cake" tobaccos... Briar Fox, Burley Cake, Kajun Kake, etc.
i also have some pipes like 'Moo just mentioned, with airholes the size of the Holland tunnel.

i haven't had that issue in a long while since smoking mostly flake or ready rubbed typed of tobaccos, the cut is too long/thick.

also, something i do now, or found myself doing a couple years ago...
when i get ready to load the bowl, i put the tobacco on the lid of the blend i'm going to have. i then fluff it up a bit with my fingers, this effectively brings the larger bits to the top, which i want to load into the bottom of the bowl for # reasons: they won't clog the airway; the space between each piece of tobacco is greater, ensuring i don't make it too tight and have a bad draw; the smaller pieces will be left for the "kindling" on top.
so, i just fluff up the tobacco, grab from the larger cuts on top and use those first. by the time i get nearly a full pipe load, there are smaller bits for the top that i use for kindling to get it going.