Astor,

Referring to English Guns and proof of English guns.

The British made Black Powder, Nitro for Black and Nitro Proofed guns.

Nitro for Black (often referred to as "Light Nitro" double circles is NOT
the same as full Nitro Proof.

I am afraid I will never recommend loading any gun with other than what it was proofed
for when made, unless it has been reproofed in the UK (or equivalent recognised country).

In my view, people in the US have some funny ideas on what is safe and what is not, expecially
when it comes to rechambering guns.

Finally, look at it this way - the English Proof laws were put there for a reason - an over
100 + years they have a wealth of experience and alot moe than what I "think" may be safe.

I know of a few guns that have blown up and most of the time it was to do with people
doing something wrong in the reloading stage !!!

Hope this helps. Just MHO.

500 Nitro