so I have a S&W Sport II, and I am strongly considering buying another BCG. Obviously there is nothing wrong with the one that came with it, but I'd like to accomplish two things with a new one:

1. The new version needs to have some kind of treatment, process or coating that makes it a bit more reliable if it has to go to a high round count between cleanings and lubrication.
Something like chrome, NP3, melonite or similar.

2. This will allow me to pillage the bolt and all the other parts off the factory BCG and store them in the stock or in a pack as back-up to breakage.

So. The question is, which BCG would you use, and why? Also, it would be helpful if the one you recommend was actually available, not some unicorn-vaporware part that no one can ever find in-stock somewhere.

Thanks in advance for any help.