Just my views and practices.
I use Mobile One as a weapons lubricant, a lot. The BCGs of my AR/M4s are 'wet' with it.
BUT, I don't put anything that will burn inside of a gas system. On a Garand this is the gas piston end of the op rod. On a M1A/M14, in the gas piston. For these areas I use 'Motor Mica', a dry non petroleum lubricant much like graphite.
I would rather have the piston dry than to burn any oil, make carbon and grind away.
Mobile One is great stuff. Might want to limit it in close fitting action parts if the weapon is to be subject to very cold temp, just on general principals.