One big advantage of hard chrome is how thin it is. It's so thin, that it doesn't interfere with the fit of any gun part, and unlike standard decorative chrome and nickel, it doesn't build up on sharp edges and corners.
There are any number of places around that offer hard chrome, but the two I'm most familiar with are Cogan/Accurate Weapon and Plating, and Metaloy.
www.apwcogan.com/Greetings.htmwww.originalmetaloy.com/These also seem to be the two that are most used by custom gun shops.
Some platers offer a discount if you disassemble the gun yourself, but in most cases, I recommend letting them do that too. Seems to be fewer problems with "missing" parts or something damaged during disassembly.
Usually everything gets plated except springs, and the ID or barrels and cylinders.
Some platers will plate the bore and chambers too.
When having plating done, you need to be specific about what you want.
Some problems I had years ago were failure to plate everything.
The original Metaloy of Dallas was the service I used first and most, until their quality started to drop off.
They sometimes had odd problems like a failure to remove the bolt from a Colt Python before plating.
When I got it back, the underside of the bolt and the frame were un-plated, AND corroded from the acid used to clean the parts.
You need to specify exactly what you want plated, and if the plater offers masking, you need to tell them what you DON'T want plated, like sights.
Hard chrome is not corrosion PROOF, nor is it something that's totally "bullet proof". It can corrode under the right circumstances, and it can be damaged if you hit it against something hard like concrete.
Even if damaged enough to break through the plating, the finish can't start flaking or peeling off.
What it IS however, is the closest thing there is to a true lifetime gun COATING.
It's VERY rust and corrosion resistant, it's MUCH harder and more durable than any of the polymer baked on finishes, and it really does last a lifetime with moderate care.
I personally recommend that you still keep a thin coat of something like CLP Breakfree on all surfaces, inside and out, and that you don't treat it any rougher than you have too.
If you have blued magazines, be sure and send them too.
Hard chrome is worth the money just for the ease of cleaning.
These days I prefer stainless steel simply because there IS no coating. It's stainless all the way through, and it can be refinished with a Scotchbrite pad.
Even stainless used under really harsh conditions can be improved with hard chrome, but for a blued gun, my opinion is there just isn't anything that offers as much as hard chrome.
There are some new finishes being experimented with, like some sort of ceramic coating, and there was some sort of carbide?? "super-finish" a couple of years ago that ran into problems, but hard chrome is still the best in my experience.