Will do Alex. There sounds like a normal full charge of propellant in it, and a 1962 headstamp shown below. This post relates to the dark violet tipped round.
Originally I thought the violet tipped round might be the XL6E1, a low pressure experimental version of the L11A1 MG Observing round used to range tank fire (because of the two knurled rings and 1962 date, with this round being produced in early 1963), but then thought this unlikely as my references stated this had a mauve coloured tip. However, I then X-Rayed the questioned round beside an L11A1, an L11A2, and an L13A1. It’s clear from the X-Ray image that the violet tipped round is loaded with an L11A1 style bullet, making this very likely to be the XL6E1 experimental low pressure MG Observing round. Chamber Pressure was dropped from 24 to 21 tons per square inch, with a loss of velocity of only 65 fps on average (down from 2965fps to 2900fps) (Labbett & Brown, 1991).
These are (in order) presumed XL6E1, L11A1, L11A2 & L13A1, the first three having steel cores with the L13A1 appearing darker with a tungsten alloy core, & you can observe the long central recess in the cores for the tracer element. The barium nitrate / magnesium flash composition is in the nose portion.
An example of the recessed steel core from a fired L11A1 / A2 MG Observing bullet.