Well, that comes from firing. Fire a lot and it’s going to get warm. The good thing is, it’s only painful if you touch it, the gun doesn’t mind until it’s red.
That is also a function of firing. Every time a bullet flies down the bore it is followed by 2,000-3,000° Gaseous plasma at about 20,000 psi.(for nine millimeter) This erodes the surface of the steel, and happens no matter how cold or hot the barrel is. Of course being excessively hot, hundreds of degrees, can accelerate this erosion. A rifle cartridge is much more intense in this fashion.
I would prefer the nitrided barrel or an actual chrome lined barrel. Luckily you have the power, or lack of it in 9mm, on your side. The more powder burned, the more erosion in the bore.
That depends on the barrel. On the specific barrel. And not something that usually comes up in an automatic firearm thread. I think it would be changing the barrel when it’s shot out, not later when it just still functions.
Really, all the same criterion we use for choosing a barrel still applies, the gun just shoots it faster.
Thick barrels soak heat longer, good for short strings and setting it down.
Flutes allegedly act like cooling fins, though the surface area is not increased much. They look nice though.
JPCustoms has some barrel heat sinks for rifles. Take a look at these for and approximate size of fin that would actually begin to help with temperature mitigation.
I’d definitely go for a nitrided barrel for increased wear resistance.
Arguably the prominent purchasing point. I do like the top one.
Stainless barrels under a handguard put me off for some reason. Even contrast painted ones are better. But that’s just me. Some humans think I’m color blind. I am, just not to the colors they think.
The shortage of contact in the barrel extension? Should that be bothering me? As well as the "no pin" on the SS.
