A version of the Lyman 429-640 Devastator. These weigh ~270 grains in 20:1.

Interesting, a wider, heavier rim on the hollow point. Have you tested them much?

20-1 should work fine.

Mick,
No, I really haven't, yet. I took a few to the range yesterday morning though. 10.5gr Unique, which may have been a bit much as the group was 2.25" at 25 yards. I'm loading a few tonight with reduced charges to try again.
I haven't had much luck with the thinner rimmed Lyman version with any charge, yet.

Of the 2 cast bullets I make for the 44 the SWC is the easiest to get along with. I've had the SWC for many years and I've worked with it a lot, I've only owned the “flying ashtray” for around 6 years now and I really haven't worked with it much. Right now they're loaded with 700X so they're pretty mild.

Those look real good Mick