Joe,
I have a couple of opinions I'll share that have worked for me.  I started with a lengthy reply then tried to remove some of my biases...

The crimp die has never given me anything but headaches- especially with cast bullets.

First, experiment with your load, a chronograph is handy - what is the powder charge and what is your velocity? I use 5744 exclusively and with some experimenting get a velocity around 1285, with a 520 to 540 grain bullet.  Much faster the recoil increases and the closest targets I shoot at in matches fall in the bullet's transonic zone (can't really say that is a proven consideration), it's usually an offhand target also.  I have shot a few of these combinations at the distance my app said I was entering that condition, my groups are usually measureably different there, so maybe there is something to it?   
Sometimes less powder makes little difference on velocity, the groups improve, recoil is less, less to burn.  Experiment with land engagement and neck tension rather than a crimp and finally, what primers are you using.  Large rifle magnum?  They're not all created equal and they're not nearly as scarce as they once were...
 
I have a couple different loads for a few different rifles running 5744 and I see very little to no unburnt powder in the bore when things all click.

My 2¢

Greg

I use a lot of 5744 in my Sharps and HiWall (both are modern replicas, one American made, the other is a Miroku).  The Sharps is a .40-90SBN and likes a good crimp.  I don't see much powder in the bore of it, using 27 grains of powder.  I simply use the seater/crimp die as included with the RCBS dies for this caliber.

In my .32-40 Hi-Wall, I'm using 14 grains of 5744 behind a 170 grain cast and it does leave quite a bit ow powder behind.  Again, I'm only crimping using the RCBS "Cowboy" 3-die set for this cartridge.

However, as a caveat, you state you're loading for a Trapdoor.  This sounds alarm bells for me.  Original or replica?  How close are your loads to the recommended maximums for that firearm?  That would taint my experimentation a great deal.  I recommend caution, it only takes one miscalculation to ruin a perfectly good firearm... not to mention the potential for injury.    Just as increasing powder charge increases pressure, so to does increasing crimp strength.  Whether you need the reminder or not, drop well below maximum charge and work your way beck up.  I hope you're using a chronograph during this testing, as pressure equals velocity, and velocity is a far better guide to pressure than physical observations.