jgalar,
I have a Marlin 1894 (microgrooves) and a Security-Six, both in 357 Magnum. I really never had much problem getting the handgun to shoot most any kind of cast bullets, but the lever gun was a major problem. As a matter of fact, it took over 20 years of reloading for it, then getting discouraged, reloading for it, then getting discouraged, reloading for it, then getting discouragedyou get the picturebefore I found a cast bullet that would shoot well in it. If memory serves me right (that can be a problem also!), I believe it was leftoverdj who suggested a heavier cast bullet for the Marlin. I believe he even sent me some to try. They were the Lyman 358429 cast bullet. They shot extremely well, so I purchased a new mold and have been extremely happy with the results of this bullet in the Security-Six and the Marlin 1894. It is a plain base bullet (Keith style, of course!) and I push it at 1600 fps from the Marlin. Leading is very minimal, but I admit, there is a bit right at the start of the rifling. It is a minor detail compared to the superb accuracy I get with it. It is very accurate in the Security-Six at around 1275 fps. The bullets weigh in at right around 170 grains. It might be something to think about. Good-luck
BCB