Did a little research and I do mean a little . This is what I found so far .
The MELONITE and QPQ process increases fatigue strength about 100% on notched components made from unalloyed steel parts and about 30-80% on parts made of alloyed steels.( like a barrel ) The hardness is maintained up to about 930�F and extends the surface life of steel tools and components exposed to heat.
This study shows how hot the external temp of a M4 barrel can get ( page 24 ). Well over 1,000 degrees with very high rates of fire and teeters right around the 900 degrees mark at moderately high fire rates . Im sure the actual bore gets much hotter then the 930 degrees the melonite is designed to withstand .What does this mean to 99.9 % of us ? Most likely nothing
Now for chrome lining I'll be back