I had a DW razorback 10mm a few years ago. It took some work from a local gunsmith to get running. I shot it quite a bit when I had it(3000 or so rounds). All factory doubletap ammo. At one time the price was not too bad and I had less children so take that for what its worth.
I could never really get good shooting it in improvised positions because the point of impact would change depending on how hard I gripped it. I dont remember exactly but I seem to remember as much as a 6" vertical difference from firing in a good squared position with strong grip to a less strong position.
Take all this with a grain of salt though because this was a few years ago. At the time I was shooting 8-10k rounds of centerfire a year but was on the upswing of learing the pistol skill-set. I still had alot to learn about marksmanship(I still do, but am in quite a different place on that curve).