Re: melonite a suppressor
We melonited the Chrome moly components of M4-SD and Spartan suppressors. The benefit is increased corrosion resistance, wear resistance, and hardness of baffles, and also a black color.
We didn't have issues because our suppressors were parts when melonited so there were no salts inside the suppressors.
We did also melonite an early Spartan first generation can as a test part (welded 304L SS) and it turned black, with some areas appearing to rust. We couldn't get the red areas to wash off. We scrapped the idea there.
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As far as actual advice, I would say don't bother. Chrome moly steel is actually pretty corrosion resistant. If you are having issues with rust I would suggest something like grill paint on the exterior to keep the air from being able to touch the suppressor.
That reduces areas that must be treated with oil to the inside, threads, and thread shoulder on the exterior.
Chrome moly has a benefit in that it is extremely strong, so even after significant corrosion has occurred the suppressor will be fit for the task.
In Europe even where suppressors like BR Tuote have very thin like .030" wall thickness, they give reasonable service lifespans- 7500-10,000 rounds.
Maxim suppressors were also steel, and there are more than a few that remain in serviceable condition 90-100 years later.
Obviously the YHM approach seemed more like "make it to the same specs as SS" < IE .125" wall thickness. (judging from weight). I didn't design the thing, but I would be surprised if the suppressor was not capable of safe performance at 30% lighter weight than the designed weight. Barring baffle strikes, your chrome moly can will probably last more than a lifetime.