Tony, I have measured factory Kynoch brass as well as factory S&B and military and they all measure O.516". Of course what is also important is that the outside edge of the rim has a small chamfer or radius otherwise it will foul in the clip where the inside bend radius is.

I have bought heaps of clips from a chap here in Australia and one in Holland as well as single ones here and there from the US and the UK. All off eBay. There are no problems so long as you don't choose a seller that uses eBay's own global shipping program or else they confiscate the clips. They refund the money to the buyer and pay the seller as well but confiscate the clips none the less, fucking bastards.

The best thing that I did was to get a clip in good condition and then polish the inside edges of the clip and radius the outer corners and make it all smooth so that the brass doesn't drag or get scratched as much.Then I have it bead blasted with very fine grit. Then I take it to a company called Guhring and have it PVD coated with Titanium Aluminum Nitride (TiN-TiAlN)( Their name for it is FIRE) which is a corrosion resistant coating which is harder than carbide and has a low co-efficient of friction and is the same colour as blueing. After that they work fantastic.

I am going to try Hydro-blasting instead of bead blasting on a couple as I believe that they will come up a little shinier than bead blasting which is more of a satin finish.

Matt.