.303 British Dummy?

Is that a regular dummy or a tinkered one?
The bullet is very magnetic. I’ve never seen a bullet like this on a .303 British.

Case is Crompton-Parkinson 1943, originally fired in Bren Gun
( Ejector indent in Edge of Primer Seat). Primer and Pocket Drilled out, about 1/4" diameter (same size as Primer)
Bullet looks like Lathe turned steel from 5/16 Rod ( correct diameter for Mk VII projectile ( .311" vs .3125")
Most Likely Home Made, not
an Official or Local Home Guard Production.
CP was an Electric Motor Manufacturer, and had an Annex to make .303 ammo, both Land Use, and RAF use. Two Plants, CP and C-P . Production ceased in 1944?

Nicely made, anyway.
Doc AV

Kings Norton produced similar bullet profiles in some of the .303 derived match ammo, but as Doc says I believe this to be homemade also.