Those who have tried Lil Gun in the 1894C are getting good results, meaning decent to very good accuracy, consistent velocity, and clean burning. Most Marlin pistol-caliber rifles shoot the heavier bullets better, longer bullet shanks seem to get along better with Micro-groove rifling than the lightweights.
The listed starting charge for Lil Gun in most sources is 16.0 grains, with a max of 18.0, but my rifle likes 15.6 to 16.2 grains, it doesn't seem to be real finicky about the load. I generally load Remington 158-grain SP's and HP's, though this rifle seems to like Hornady bullets quite a bit. Actually, I have yet to see a rifle that didn't shoot the Hornady's well, period, and that seems to apply to most pistols as well. They're making good stuff in Grand Island.
Velocity with the listed load gives me 1750 fps average velocity from the 18.5" barrel, and accuracy that will make you sit up and take notice. It would make a fine deer load out to 125 yards or so with soft points, given good placement, as always. It will pretty much do this at 50 yards off a rest, for as long as I care to keep stuffing cartridges into it. Hard not to love a gun that makes you look good, eh?
