I thought I had this one.   

One caution for you in dealing with these old  British cartridges.

First the British made the rifles.  There was no real standardization. 

In 1904 Eley and others settled on standards.   

Then in the 1970's CIP came and created new standards.

Often none of the three are the same but are intended to be the same..

Looking at my books, I see no other issues.   

In these  old cartridge some times there is a BPE version and NE version.  Then sometimes there is an EXP version. It can difficult to know if this EXP is the BPE version or the  NE.  Fortunately it appears in my references there  is only one 500/450 #1 Express and it is listed as a blackpowder cartridge.

That being the case you only have to make sure if you are going have a reamer made, that the reamer maker is working to the same standard/drawing as the die maker.

Good luck, that cartridge has a good reputation.


 

curdog wrote on Jul 20^th, 2025 at 2:03pm:


I kind of suspected, but wasn't sure.  People often come up with these guns and don't understand what they have.

...If you ever need a WR Musket No. 2 reamer, I can help.  I also have a 577/450 reamer, but it is CIP measurements, sharp flat shoulders, not ogee's.  I have a couple others, but don't recall which.

Here's a reamer I sold on and wish I never had.   .375 H&H Flanged  Magnum.  JGS made it.