I HAVE NOT YET FIRED MY AR LE 6920 it's on the outer face of the chamber what should i do!!
That number 4 marked on the barrel extension, not the chamber, is Colt's standard markings on all carbines with M4 type feedramps, it's normal.
My other 6721 carbines that also have M4 feedramps also have that same mark.
Some other companies do the same markings on their barrel extensions, some also on the left side of the chamber, and it varies with numbers, letters or sometimes symbols like for example a star symbol.
Clean your carbine well, then lube it well, get good ammo and mags and have fun with your 6920 carbine.