I'm not sure what a nerf dart looks like, looks like I need to find out. Any idea what they weigh?
As far as the 35mm cases in the Atlas hulls...
Wrapped each one with duct tape so there was a snug fit.
Filled with sand/chalk ... about 1.5 ounces total.
Seated container as far down there as it would go cap end up.
25 grains 2F - got about 5 foot range.
40 grains of 2F - maybe 10 foot.
40 grains 3F - not sure where it went, as by then I wasn't walking out to my backyard range but just shooting behind my house which overlooks a hill going into the woods. It went "quite a way" is all I can say, but not like what a turned down 40mm "booster case" with 25 grains of 2F would do.
I backed it down to 30 grains of 3F and it was back to landing not too far from mwhere I was standing.
I was a little uncertain about putting effort into working up a load using 3F as I don't really know what the hell I am doing yet and need to ask around a bit before doing more work with the stuff. The case looked fine afterwords, so it couldn'ta been to bad. Still, I decided to wait a bit and ask around before continuing to play with the Altas cases.
For what it's worth, I also played with the longer White nylon FTF cases. I only tried them with 25 grains of 2F. They worked better than the yellow atlas cases but nothing like what I could get to happen out of an aluminum case (even a really short one).
I am thinking it's gotta have something to do with the wall thickness of the plastic cases and how they don't allow me to load the film containers top end down, which might have something to do with getting a better seal in the bore, but that is all just guessing.
Need to mess with it again someday when it warms up. I'm about 40 miles north of you as far as I can guess, and if I'm right you know it isn't gunna be shooin weather for the next few days.