I do not have any kind or damper on the stove, barometric or manual. I did some mods over the weekend (and made a huge mess in the finished basement). I cut the rear half of the stove collar off flush with the "ceiling" of the stove (it was protruding 1-1/2" down into the firebox). I also installed a hinged smoke flap that reduces the load door height from 11" to 7". Another unrelated modification was the installation of secondary preheated air.
The mods were fairly productive. I think the hinged smoke flap did the most good. I doubt the stove collar did much, but I wanted to try it. I still get a slight amount of smoke curling out at the left edge of the door opening . I still need to attach a baffle slide to pull my baffle plate to the front of the stove and see if that helps. The preheated secondary is not quite functional, as I have to drill a 1" hole in the front of the stove, and I'm having a hard time allowing myself to do it unless it's absolutely necessary. I don't seem to be clogging up my chimney after burning coal for 2 months. The interior smoke pipe gets some buildup, but not much if I burn it hot.
I have not tried a candle test in my thimble. To reiterate my chimney setup, I have 18" of vertical 6" dia. double wall smoke pipe exiting the stove, then a 90 elbow, 12" horizontal to my thimble, a chimney tee, and then 12' of metalbestos pipe up the outside of the house.
When I lit the stove after all the mods, I was impressed with the draft when I warmed the flue with paper. Sure seemed like good draft to me. We get very little wind in the Big Horn basin of Wyoming, so I don't usually have any draft help or hindrance from wind.
I'll post some more on this when I get the baffle slide done. For now, I think I have the smoke issue improved, and can certainly live with what I have now even if it gets no better.
BTW - when I was doing the mods this weekend, I took the opportunity to dump the grates - I was surprised at how many rocks, clinkers, etc were plugging up the grates. After cleaning, I get much better air distribution through the grates, and a better coal bed. Looks like I'll have to inspect/clean the grates monthly or so.
I think I'm to the point where I'm ready to share the stove drawings/plans. I'll edit them to show the mods and get them posted.
Thanks again for the input.