I bought an IMI .44 DE with a six inch barrel about 5 years ago, for a song, and just started shooting it.  The gun had no visible wear and the action seems smooth.  However, after the first shot, and follow ups, when the slide strips off another round and loads it into the chamber the slide wont close and is stuck open about 1/2 inch.  It doesn't happen every shot but about 75% of the time.  It happens more with heavy bullets than with light ones.  I have tried my own hand loads and factory Winchester ammo with the same results.  The slide closes fine when there is no ammo is present.  The extractor seems to be the only variant here but there is no wear on it showing that it is hitting the chamber rim???  Anyone have this issue withe their DE in .44 mag?

The one I owned was very fussy on ammo. It came with a list of approved ammo that would feed it.

My second one did the same thing. I sold it and a few years later bought a new one. I hope you figure it out as I never did and just got tired of trying.

Did you have the same problem?

Yup. If I used the approved ammo I had no problems.

Very finicky weapon, I try to use Truncated soft point when I can find it, mags can be an issue as well. I did recently put in a new spring kit from Falcon Arms that is supposed to help as well but have yet to
shoot it with the new kit installed. Worst case scenario send it back and they will fix it for free, I'm sure they've dealt with this issue in the past.

According to the Magnum Research website, I'm 'limp-wristing" the gun preventing the action from snapping closed.  Back to the range I guess.

It's probably a Mark VII gun.  The main springs are weak and need to be replaced.  You can buy them online at the Magnum Research web page.