UK L11A2 .50 cal - did they do tungsten HC?

This has an FMJ bullet with 1k/2k crimp/id cannelures, but no tip color.
HS is K 70 L11A2

Sticker on round says “Tungsten carbide”.

I don’t see that anywhere in Fuchs’ book.

Observation rounds K69,70 and 71 L11A2 all weighed 111-114g. This one is 130+g

I wonder if it might be loaded with a prototype projectile for the L13A1 observing round? From Tony Edwards’ old site: a heavier observing projectile was developed in the 60s and they tried various tungsten alloy cores to achieve this. Projectile weights were 955-975 grains vs. 626 grains for the L11A1/A2. That weight difference matches up with your specimen fairly well.

Here’s the page: