Sorry in advance for the long post but I think it will be of help...
I have one that I bought used from the EE forums here and it shoots with no issues now.
Before purchasing it I read up on it and heard all the horror stories and prepared myself for a picky shooter. One thing that I came across on a DE forum from the folks who had few issues with their DE's is that the springs were usually at fault...They need to be changed after a few thousand rounds OR every couple of years.So I bought all the recommended brands that I could find in 240gr and 180gr UMC Remington .44mag ammo. I also order a spring tune up kit directly from Magnum Research.
The gun arrives and time to experiment ... I head to the range with a load of 5 different brands/models of recommended ammo and the DE as I received it (only a regular cleaning and oiling). It jams every two rounds and I never get to finish testing all of the ammo I brought.. what did i get myself into?
I mention to another forum member that I'm having issues with it so he invites me to his club to see if he can help. No further luck, still jams every couple of rounds or so. I meet two of his club mates that have DE's and boy did they let me know what they thought of their pieces of crap lol. One thing that keeps popping up is that they have yet to change their springs...
So I go home that night and replace ALL the springs and head off the next day with another forum member who had invited me to Sharon Gun Club. I load up the Hebrew Hammer (lol, my pet name for my DE) with the same brands that were jamming....... I fired off an entire magazine and none jammed or FTF! Next brand same results, and the next brand and the next brand and the next brand

Only on the last mag I had 2 jams, but my friend tells me that I was limp wristing [no surprise after shooting that many successive rounds out of the beast].
I'd say order the spring tuneup kit and give it a try before you sell her out of frustration. I'm happy I did and even sent it off to be hard chromed - shot it the day after I got it back and it functioned flawlessly.
Oh, another tip.. don't cup the magazine base plate as you may push the mag up and that would also cause problems with jamming.