Nope, haven't tried the scabbard, yet. But I think it'll hold a back-quiver full of arrows nicely on an overnighter. Sorry for the late reply.

I tested the loads for the .300H&H today (thanks to John M. for the loan of the chrony), and they (PPSN and Hydro, both 180 grains) do about 2850fps. They seem to work, anyway.