Do NOT take it to a production plating facility. They won't know how to properly disassemble, then reassemble your gun properly, nor will they know what not to plate. Even their process is not the best way to nickle plate a gun. Most platers use an electroplating process. It is fast and inexpensive, but uneven (especially on gun parts). Electrop0lating will plate thicker near sharp edges, and thinner on inside curved parts. Also, it is often porous, and so to have good corrosion resistance, it is often done too thick to allow close-tolerance parts like in firearms to fit properly.
Electroless nickle plating is far superior to electroplating for firearms. The thickness of the plating is not effected by the shape of the part, and thus, goes on evenly, and gives complete coverage even when only a few ten thousandths of and inch thick. This provides superior corrosion resistance and will not interfere with proper fitting of the parts.
I had a gun in my shop that had been taken to a production plater. The gun was a top-break revolver, and it looks like it was plated as three assemblies; the barrel assembly, the cylinder, and the complete frame. By replacing all the springs, and grinding off the plating in key areas, I was able to get the gun functioning again, but any collector value has been destroyed, and the gun still looks bad.