Identify this casing.

[Germz]

I have no clue. Found it a couple days ago. Headstamp says RG 83

[Germz]

Ok apparently this was manufactured in the UK,

RG (1940 - Present) Royal Ordnance Factory Radway Green - Radway Green, Cheshire; England, United Kingdom.

[Rock6.3]

http://www.cartrology.com/browse-ammunition.php?mode=item&ID=627

http://cartridgecollectors.org/cmo/cmo05oct.htm

[Frotz]

Where'd you find it?

[maxx03]

Interesting find op. I would also like to know where you found it.

[Germz]

On the ground in Camp Pendleton.

[6mmintl]

smaw spotter cartridge as show above

[ducky_0811]

6mm beat me to it, that sir, is what happens when a 9mm and a 7.62 nato go to the bar and have a quicky. It fires a tracer round that has the same balistic flight path as a SMAAW rocket, you fire the spotter round to make sure you're hold is correct, the. Fire the rocket and destroy Mr tank

[maxx03]

On the ground in Camp Pendleton.

That makes sense.Thanks for sharing op.

[klewan]

That's one of those 'gayhe' cartridges...like they use in the Castro District...

[pyromensch]

similar to the 50 cal spotter round, on the 106 recoiless
(in design)