Had a lot of fun with this one over the years.
Brass is darned near extinct but you can make it in a few steps from 32-20 Starline brass. Go over to castboolits and the case forming section for a nice discussion of this conversion.
Lots of load info in a sticky thread on Marlin owners forum\reloading section.
I've used three different molds over the last 30 years, Lyman 257260(GC 70gr) likes speed in my rifle, a group buy 6 cavity 80gr. GC round flat nose that shoots great, and my latest, a 85gr. 257283 clone from NOE molds.
http://noebulletmolds.com/NV/index.php?cPath=26_171&osCsid=j48rdd49k7pnqlivelff6tvp52I bought mine as a flat base for light practice loads. I've been using PC with 9.3gr 4198 and hardly load anything else anymore.
Great small game round