You can take out the filter and cut it in half. This will prevent ashes from coming up the stem but will still allow a smooth draw..... It is recommended that the filter be changed after 10 pipefuls..... I usually wait until the draw becomes restricted, but that's because I'm lazy.
A further suggestion would be to check out the videos at Aristocob.com. Scott has a video on how to fix a too loose or too tight stem. He also has a lot of interesting video info about cobs on the site.
I find I smoke in short spurts..... 10-20 minutes..... then off to do something else.... MM offers the pony and their hardwoods have small bowls too.... and my cheap Indian smokeshop tobacco is dry and smokes fast.... I wish I could sit still for an hour of enjoyment..... alas, it is not to be.
:puffpipe: Tis' interesting how each of you deal with the same problem.... I recently purchased the grabbag from MM.... when I offered my wife her choice of cobs, she declined (she doesn't smoke).... so here I sit puffing away... in peace.... thankfully