When Hornady stopped producing the 410 gr 50 cal bullet the Lyman plains bullet was one of the first ones I tried. That would have been back in 2006 I think. Back then I was just starting to cast and had no Idea about lead hardness and its effects on bullets. All I knew at the time was the Hornady 410 shot really well.
I started shooting the Lyman bullet and I was not impressed with it. 50 yard groups were larger than 5".
I ended up going with the paper patched Lee 500 S&W bullet as my go to bullet and never went back.
That said back then when I tried the plains bullet I don't have a clue what the hardness was. I also didn't know at the time that my barrel likes harder lead. All my bullets were coming out at .504 and the mould was supposed to be a .508. I sent it back and Lyman said it was within spec.
I know that I did try it again after I was developing the S&W bullet. I even tried paper patching it at one point. But I know I didn't adjust hardness, compression cast, or try different paper.
I sold my mould and wrote it off.
Looking back on it, I can see that now I would try a slightly harder lead. I would also try different lube, and paper. When I started to use a ladle to compression cast about 2008 I know that took my bullets to a higher level.
I didn't have good luck with the mould, but I recognize now that my lack of casting knowledge, and load development was more to blame than anything else.