Curious about Oerlikon markings

Hello, I have a round of what I believe to be 20mm Oerlikon. It has SWN/68/56/HF IT/TNT/13Z

I’ve found out the SWN means it was produced in Royal Ordnance Factory Swynnerton, I’m guessing 56 was the year of production, and it’s obvious what TNT is, but I’m curious about the “HF IT” marking and the “13Z” marking. I would have expected something like HE IT (High Explosive Incendiary Tracer) but I’m sure it’s an F as the shell is well preserved.

I’m also curious about what appears to be paper residue stuck to the side of the shell.

Does anyone know what the HF IT and 13Z might indicate and what the paper-like material might be? Thanks.

Hello, it looks like a fired case that was converted into a lighter. You can try removing the “bullet” cap with your fingers; they usually come off easily.

ROF Swynnerton is the filling factory and the case was likely manufactured by ROG Radway Green (I assume the headstamp is RG 55 OeZ).

“HFIT” is a badly marked “HEIT” and “13Z” is the Mark of the round (Mk. 13.z).