Improving Mortise Gurgle

[kf5eqv]

I got a predrilled briar kit recently. Today is the first time I smoked it but because of the way the mortise is drilled like a funnel, it tends to gurgle and generally not smoke as well as I think it should.
I'm wondering what method would be best to fix this?
My first thought was to use a wet tissue, stick it into the mortise firmly and then slowly remove to get the shape. I would then carve down an existing stem to make an insert that fits inside to smooth the airflow.

Then I thought, maybe I'm over-thinking this. Should I just cut down a filter and stick it in there?
What are the thoughts of the more experienced smokers/pipesmiths out there?

 

[pentangle]

It's a straight or bent kit?

 

[kf5eqv]

Bent.

 

[pentangle]

If the shank hole isn't precisely done don't meet in the same line the tenon hole, and if between tenon and the end of the mortize the's a chamber due to an incorrect mortize drill (to deep) the's a chamber and the smoke condenses.In a bent kit that could happen more frequently than in a straight

 

[kf5eqv]

Thanks for responding.
That is the problem. The kit came with the mortise drilled out in a funnel shape narrowing down to where it meets the bowl, so there is a air chamber no matter what stem I use. I suppose I should have been more clear in the original post.
Is there a fix? I tried fitting a piece cut off of a Dr. Grabow filter in the "chamber" ahead of the stem's tenon and that helped, but if there is a more permanent fix?
I guess I'm just looking for advice from those more experienced in the pipesmithing arts than myself in dealing with this problem.

 

[pentangle]

Try to put a tube stinger like dunhill into the tenon till the chamber bore or better enlarge the mortize hole to fit a new stem with tenon filter for 6mm or 9mm filters. At that point guess only a filter like the balsa by Savinelly could help you

 

[kf5eqv]

I think the modified Grabow filter is going to work for this pipe. I might do something else later depending on how much maintenence this system ends up being. Thanks for the help!
My next pipe won't be pre-drilled, that's for sure.