I have not handled a Lyman in-line but I do own a Ruger 77/50.
The Ruger I have is the one with a hardwood stock and blue barrel. It has a working 21" barrel and is very accurate. I bought an after market trigger sear and spring to improve upon the factory trigger. I tried the Cabela's 209 conversion but did not like it and was satisfied with #11 cap and T7 loose powder. I have not shot it for a couple of years because I prefer the .45 cal Knight DISC Elite that I have. I think the load I was using in the Ruger was 85 gr. FFFg T7, .45 cal 250 gr XTP/SST in a 50/45 Harvester smooth short black sabot and CCI #11 cap. With mine, I need to make sure that the #11 cap is seated fully or the first pull of the trigger with seat it for me and not go off. It is a light, well balanced rifle and have no plans to part with mine.