About the only thing you can check is to take the stock off and make sure the trigger housing is not loose in the rail. I'd spray carburator cleaner, brake cleaner, or starting fluid in there ans "wash" it out, relube w/ Tri-Flow and see what ya got. If none of the above help, call Danny Miller.
back in my paintball days I used to modify the triggers on my paintball guns pretty elaborately with various travel limiters, spring swapsand shims, however paintball guns are in a little different class...
I'msure theres probably alot than can be done to impove the trigger but I'd be extremely leary about messing with my crossbow's trigger unless I could take it apart, study its design and knew exactly how it was put together and how it works and even then I highly doubt I'd do much, if anything,with it, I'm surethe outcomecould be just as dangerous as it seems it could be...
I have thought about the idea some though, a limiting screw through the back of the trigger guard would take alot of the overtravel out of the trigger, tightenthe "feel"up some andwouldnt have anyimpact on the actual trigger itself,but it was just a thought, my trigger is more than tolerable and messing with itscares me...
Excals are known for quality triggers. Everyone i've ever shot has been swell. I forgot to add in my previous post that after degreasing, I'd take the air hose to it. Wax can build up in the trigger box, along w/ years of dirt, crap, and crud. Let us know how it works out for ya??
Edited to add: one other thing. If you have any "Loc-Tite" on your stock screws, it would pay you to take a steel nut the same size [think 10-32] and "chase" the threads to get rid of old Loc-tite. If you strip a screw hole in rail [any excal body] pm me, I have beau-coup Heli-coils from my lesson learned here, lol.
Not a guru by any stretch of the mind, lol. But, for awhile I had 4 Excals here and 2 custom wood stocks and was playing "Musical Stocks" switching them around looking for the one perfect set-up. Since I tend to learn life's little lessons the hard way, I can tell ya'll one of them is built up old dried loc-tite on steel screws going into threaded aluminum holes somewhat repeatedly is asking for trouble, lol. the first one I stripped I had heli-arced and I redrilled and tapped it. When I tore that one up yet again, lol. I went w/ heli-coils, which as you all know are steel vs aluminum. End of problem, except ya gotta buy about 20 of the little rascals in a pack. I'm only dumb enough to need maybe a couple more in my life time, lol, so the rest are available for anyone else. {Btw: conclusion of musical stocks and 4 Excals is the Phoenix w/ factory stock.}
I had the same problem with the two Excaliburs I have owned. I lubed the trigger with a teflon based spray lube (stuck the little plastic tube right up into the trigger housing without taking the stock off) the takeup vanished and reduced creep substantially.
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Vortex, Phoenix, Cyclone, single shot rifles and handguns.
Only accurate guns- and bows - are interesting.
Trigger creep
......I got me a good selection also from working and oppsing on my olderHarley/s 
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