AR Barrel Extensions

[MikeD31]

Has anyone every seen an upper receiver with the barrel extension as an integral piece? It doesn't seem to me like it would be difficult from a manufacturing perspective (I have no manufacturing background so maybe I'm wrong) but I've never seen one and for all the discussion on AR's I've never even heard this subject come up. Can any of the smiths on here educate me on the reasoning behind the separate component vice having it as part of the receiver? Thoughts?

Mike

 

[orwapitihunter]

Upper receivers are usually made of aluminum. The extension is steel, and it needs to be steel as the bolt head locks into it.

 

[MikeD31]

Thanks, I thought too deep into it and didn't consider the obvious.