Since Woodleigh burned down in Australia there aren't really any options for good jacketed bullets. I'd try making a hard-cast, jacketed and gas-checked bullet. Most .510 barrels have a very gentle twist like 1:18 and it might work.
I'm making these using an NOE mould:
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I haven't pushed them that fast yet but plan to this summer.
Which mold is that propliner? Weight? How fast do you figure you could shoot that and what are you using them in?
I checked out NOE and most molds are out of stock unfortunately.
Are you in Calgary by chance?