As said, there are a number of companies who have proprietary names like Armoloy, Metaloy, SS Metalife, etc, but it's all hard chrome.
The only practical way to get hard chrome off is as above, to reverse the electroplating process so the hard chrome is de-pated and removed.
To do this you definitely want a professional GUN plater company to do the work.
Good choices for removal would be APW/Cogan, Ford's, Armoloy, Metaloy, or Techplate Inc.
Acids will not remove hard chrome, and bead blasting will not get ALL of it off.
It may look like it's all off, but if you attempt to apply a chemical finish like bluing or Parkerizing the gun will come out looking like it's covered with white freckles.
That's the tiny areas where the blasting failed to remove it all.
Plus, companies like Cogan and Ford's can apply whatever new type of finish you want after removal of the hard chrome. They offer just about every type of gun finish available.