MonoLithic uppers?

[skyfish]

These seem to be more common and more popular, I can see a slight advantage for rail alignment and stability. But never seen one in person.

Also, how do you attach/thread a barrel?

Also, like the pic off the AA piston in Flat Dark Earth. For some reason I like a non-black "black rifle".

[rasp65]

Here are the instructions for the Mega Monolithic uppers http://megamachineshop.com/pdf/MTS-BARREL-INSTALLATION-INSTRUCTIONS.pdf