30mm x 86b LV (low velocity) ,30mm ADEN LV.
That specimen looks like one of the US versions.
If it is British the colour for experimental is purple. It could well be purple but the colour of the surface behind the projectile may be interfering with the real colour.
Are there any stampings on the case belted base rim?
Thanks Dave,
For some reason i thought the brown stencilled projs. were American,I think the style of marking must have fooled me.