I saw Brownells is selling them now. Any real benefit to them?

imo just color

Increased surface hardness and corrosion resistance...
 

If you want to do cyclic rates of fire and multiple mag dumps then yes.  I destroyed the heat treat on a standard tube and later had corrosion issues.  Now I use the melonited tubes for anything I want to shoot fast.









       
 

The main advantage of Melonite is it reduces friction; and lessens surface wear, which would extend a gas tubes life. Melonite creates a new compound layer in the top 10-20 microns of the surface, creating a very hard, slick surface. This surface is so slick that carbon does not easily adhere, so it is easier for the gas tube to remain clean.

Originally, the AR-15 did not use a stainless steel gas tube. The switch was made to stainless steel due to the alloy reduced the amount of carbon accumulation within the gas tube. Additionally in a report dated November of 1960, it was determined that carbine length stainless steel gas tubes have the capability to withstand as much as 9,000 rounds of firing while continuing to serve as a suitable power source. Therefore, why not run a gas tube with a Melonite finish when they are priced around the same as stainless gas tubes, and offer the advantageous listed above.

Melonite tubes cost about twice as much as standard. $13 vs $8 ish

At $15 shipped they are a good deal.  While you could save about 30% if you happen to have an order in for another part, the free shipping at AIM is great for a standalone order.



http://www.aimsurplus.com/product.aspx?groupid=1005&name=Spike's+Tactical+304+Melonite+Gas+Tubes

       
 

I have a couple and they are nice. I have some regular ole tubes as well, does the same thing. The fact that they are black is the only advantage I can find for a semi-auto. They're not expensive, get two!

Sure. Gas tubes at that price point can be found. Below are 10 websites that offer gas tubes, many from various manufacturers, and if you look at the prices listed; they are comparable to a Melonite Gas Tube. Obviously, Melonite gas tubes will price a little more, that's obviously a given.

Joe Bob Outfitters — Gas Tubes
Brownell's — Gas Tubes
BCM — Gas Tubes
Midway USA — Gas Tubes
Primary Arms — Gas Tubes
New Frontier Armory — Gas Tubes
Windham Weaponry — Gas Tubes
Rainier Arms — Gas Tubes
Wilson Combat — Gas Tubes
PSA — Gas Tubes

Having a black tube IS nice when it's exposed in a relatively open forearm like my Fortis.

I suspect spikes started making melonite gas tubes when they started making 5.45 uppers

I believe so.

Well that's your answer to where the benefit is.

So no benefit with non corrosive 5.56mm ammo. Only worth it for corrosive comblock 5.45 builds?

Melonite flash scales at approx 1100f.  You can get a tube that hot.  It is a bad application for melonite imo. The increased wear resistance is only a couple ten thousandths thick on stainless steel and the only place that applies is the gas key interface. Due to the sliding impact there I would expect the finish to wear anyway on account of the underlying material being too soft to support the hard surface layer.

If you need a high temp tube get one of these:

http://www.v7weaponsystems.com/products/v7-extreme-environment-gas-tube

Wes

V7 makes some amazing stuff. They would quickly separate me from any extra cash I had laying around, assuming I had any that is.....

Not knocking the product. I like V7's stuff. But that is the worst product demonstration video ever. They show a normal gas tube fail. Then that's it, lol. Shows nothing of their product. They don't show it being used or even show it to you, (not that there's much to see, it's a gas tube after all) they just describe it to you. They need to have a part two to that video and show their tube being abused.