Why are AR rails almost exclusively 6061 aluminum?

[tRidiot]

I don't get it... is there a practical reason? 7075 is stronger from all I have read. We look for lowers with 7075 aluminum construction (usually). We recommend it. Not that 6061 isn't good, I suppose, I'm just wondering... rails tend to get beat up a bit with tossing the rifle around, attaching, removing and reattaching auxiliary components... is it JUST a cost issue? Is it that much significantly harder to mill or cast 7075 that it's cost-prohibitive to do so?

Just curious.

 

[Shootin 4 Fun]

Because 6061 is strong enough.

 

[aviator41]

Not sure 7071 would get less dinged up.

What typically gets dinged up is the finish, not the metal.

 

[Johnny]

IIRC 7075 has more Zinc in it. Which poses problems when it comes to the anodizing. I could be wrong though.

 

[Boehlertaught]

Maybe due to the fact that the military was the original customer the specs were written around. And, since 6061 is strong enough, it was believed the military would replace and worn or broken parts on a regular basis. ???

 

[saltydecimator]

so by strong enough we mean cost. 7075 is more expensive, and why over do it.

if ultimate strength and corrosion resitance is your aim, get this in stainless

http://www.theflatspot.net/ar-15-receiver-flat.html