Hi Bill

Yes, originally they asked me to bring primed cases and heads along and said that they would make up blackpowder loads for proof?! as these would stress the action. I can only presume that this is due to the pressure curve, or that they have data for the blackpowder loads that they consider more reliable than the nitro powders.
In the event however I had 480 grain woodleigh solids and they dident want to put blackpowder behind a jacketed head hence the use of my rounds which I had incidentally only brought along as I was going to be cheeky and ask them to test fire them as well in the gun, as they are an extrapolation of the data in A squares manual. A square use 113.5 of H 4831 behind a 465 gn head. I was loaded at 111.5 behind a 480 gn head with a pinch of filler. I was nervous of this as I have never inserted filler in a cartridge before.
It was as you say quite a day . I have had little free time from my business and having booked this day off weeks ago we got 4" of snow overnight and the centre of london was a relative gohst town at 8.30 am. It took me an hour to do a 20 minute journey.

Regards Mark