Try Huntington's....
Hi Catch,
Kudos to you for working with the .455 Webley! The fun factor goes off the chart once you can put together good loads.
I use the Hornady brass, 4.3 grains Unique, and my own alloy cast into the 265 gr. RNHB base bullet lubed with SPG.
It's not worth it to me to mess with cutting down .45 LC cases when Huntington's has Hornady .455 Webley cases in stock.
I roll my own: I bought the RCBS 45-265-RNBH mould and even cast my own! Go to the Midway site, look up the RCBS mould, and you can read my full review of it there.
In a nutshell, I use a SOFT alloy that works out to about 40:1. My formula is ten pounds scrap lead, ten pounds wheel weights, and add 4/10 pounds Tin (or a 1 pound bar of 50/50 solder).
The next trick is that your mould and alloy have to be very hot to cast right. It takes me about 15 castings before it's at that sweet temperature.
The hollow base design adds extra problems to the casting process: You can wind up with base voids. But, again, if you cast hot, and leave a generous sprue on top of the mould, it practically eliminates the voids.
I resize the bullets to about .4553 in my Lubrisizer, and lube with SPG: Results are ZERO leading, and accurate load, and a crapload of fun!
Beware of Fiocchi brass: Some of it has small pistol primers. I'm stuck with about 200 casings, some still with factory loadings.
Fiocchi factory ammo sucks. It's dirty, the cases are scarred by the factory loading equipment, and it leads the snot out of the barrels. Bah. Avoid if possible.
But, since ANY .455 brass is precious as gold, I save it, and just segregate it. I shoot and load the Fiocchi stuff separate from the Hornady.
Last weekend I went into a marathon casting & reloading session, and did almost 500 Webleys... I won't be happy until I get another 400 socked away (next paycheck!). I like to have at least 1000 rounds loaded per caliber that I run.
BTW: I use a Webley Mark VI that's been halfway converted to .45 ACP. There's enough of a lip on the ratchet to hold up a .455 casing. I also lucked into a S & W second model Hand Ejector (Canadian contract, 1915). Both guns shoot about point of aim 50-75 yards out. They're surprisingly accurate considering the fixed sights. I enjoy popping puddles out about 75 yards... There's nothing like that "sploosh" as great geysers of water go flying into the air!
If I were you, I'd drop your load to no more than 4.3 grains Unique... That's max for the Webleys proper. Pressure wants to be held to no more than 12,600 or so PSI. 5 grains puts you well over that.
Yes, a lot of the guns were converted to .45 ACP, but it runs more like 18,000 PSI. Not adviseable for long term use. It may have been done as an expedient to sell the guns to a US market that had an abundance of .45 and a lack of .455 ammo, but that doen't mean it's smart.
Every time you fire a .45 ACP in a Webley, it's essentially firing a proof round.
Do yourself a favor, and run the gun like it was meant to. It's not good to push old iron too hard anyways.
Enjoy the Webley, and drop me an email if you want any further info.
BTW: Where are you? I still own a house N of AVL, but had to move due to the job market. Sure miss the hills...
Happy Shootin'! -Tom