Barrel differences

[Ruezim]

I am building an AR pistol and in the process of picking out my barrel. I am wondering about the differences in the finish of the barrels. I would like to go with an 8” but do not know enough about the differences between the four. I am not looking for suggestions of other manufactures just the finishes on these barrels. What are the advantages and disadvantages between them? I have looked around and was not able to find much information comparing the different finishes. Thanks for all the help.

www.shop.masdefense.com/8-300-AAC-BLACKOUT-1x8-CHROME-MOLY-BARREL-838MABL.htm
www.shop.masdefense.com/8-300-AAC-BLACKOUT-1x8-MELONITE-NITRIDE-BARREL-838MMNABL.htm
www.shop.masdefense.com/8-300-AAC-BLACKOUT-1x8-STAINLESS-STEEL-BARREL-838MSSABL.htm
www.shop.masdefense.com/85-300-AAC-BLACKOUT-1x8-MID-WEIGHT-4142-HARDENED-STEEL-BARREL-838MHDBL.htm

Ruezim

 

[HOOfan_1]

#1 has a parkarized finish (phosphate) doesn't say if it is chrome lined or not though the parkarizing helps prevent rust, but the best way it helps prevent rust is holding oil
#2 is nitrocarburized, means it is dipped in a molten salt solution which hardens the surface of the steel and makes it corrosion resistant. It should give better corrosion resistance than the phosphating and better accuracy and corrosion resistance than chrome lining
#3 is Stainless steel
#4 4142 steel...they don't say what steel #1 and #2 are...4142 is Chorme Moly steel too...but it has a lower carbon content and is not as hard as 4150 steel which many barrels are made from

I'd probably choose #2 if I were buying