Tall....200's & 240's work well in my Marlin 336 .44 built in '64 with Micro-Groove rifling. They also work well in my son's 1894 Marlin. Both cast and Hornady, Remington and Sierra's will feed well in both guns. For our use, on deer here in KY, they do very well indeed, and there are no problems with stabilization, nor recoil from the relatively light Marlins.
As for cast: I use straight wheel weight alloy +1-2% tin for mold fill out. The very best are Lyman's 429244 & 429215, both gas check types (GC) based on the old Thompson design. The 429244 goes ~255 grains from my mold and drops at 0 .432" dia. with the above alloy. The 429215 weighs in at ~225 gr with the same alloy and mic's the same as well. Of the two, the 429215 feeds just a little better, but both will cycle through the 336 and 1894 designs if the lever is operated as you would for a 2nd shot at a wounded deer...aggressively.
Ranch Dog's old design: 432.265 GC is also a great cast bullet in both of our guns. IIRC, it was designed specifically for use in Marlin lever guns and feeds the best of any cast LSWC I have tried. I size it to 0.432+". It's an older Lee produced model in aluminum, and casts well. It features a wide flat point that's a good killer on deer. I've found it to be equally accurate as the Lymans listed above as well as my favorite jacketed type: Hornady's 240 gr XTP. All of the Lyman's & Ranch Dog molds are LSWC's offering through and through penetration on deer hit through the slats and/or the shoulders. The Hornady 240 XTP gives good penetration & expansion for chest shot deer.
Conversely, Keith's famous 429421, the Lyman version, does not feed well through either gun and drops slightly undersize for rifle use...around 0.430", which is ok for the handguns but leads somewhat with the Marlin carbines. Nor is it as accurate as the 429244 or 439215 GC Lymans.
For all of the above cast designs, I use 296, Accurate #9 or 2400 powders with charges that usually run a grain or two below max from the Lyman Cast Bullet Manual. Accuracy is good, averaging ~2" out 75 yds or so with a 2.5x scope mounted and shot from a rest. Leading has not been an issue whatsoever and that's with air cooled bullets. BTW, with 296 & #9 I use magnum LR primers, and standard types with 2400.
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While I've had some success, using Missouri Bullet Co's 240 gr LSWCs, accuracy was not as good; ~3+" at 50 yds, scoped; with some leading issues as well.
With both Marlins, cast bullet diameters make an enormous difference in both accuracy and leading, more so than does alloy/lube in my experience. I use the biggest dia. that'll chamber.... that's 0.432+". I lube with a ancient Lyman 450 sizer, using a sizing die honed to apply lube only; accepting the 'as cast' dia.
Be aware that these dia's may be too big to chamber in some guns and may also have pressure issues in revolvers. In my .44 cal. guns (Ruger .44 Spl's, BH's, and a quartet of Smith .44 Magnums), I size to 0.430" which gives me good sub-2" groups at 25 yds from a solid rest. I do not use my hand loaded rifle and handgun rounds interchangeably. To positively identify rifle only rounds, I color code their primers with a magic marker and also run a red marker band around each bullet nose just above the scraping band.
HTH's Rod
