I'm waiting on a mold I ordered from Accurate Molds and just had to shoot something out of the new to me gun I got. It's a 1933 JP Sauer Drilling with a 8x57 JR rifle barrel. I slugged the barrel and took a chamber cast to order my mold and found out the groove diameter is .319. I don't have any molds closer to that then .315 for my .32 revolver. I did have 50 or so .318 buckshot salvaged from some old buckshot loads that got wet. I lubed with liquid lube last night and loaded some today with 3 grains of 700X. This load worked well for my 9.3x74 using .375 RBs so I figured it was a good place to start. The results are below. When I went to 4 grains 700X they started to throw fliers. Opened up to over 4" at the same 50 foot distance. The Drilling has a set trigger and I know it surprised me a few times. I only have 20 cases so far and they went fast.
I think round ball loads are a great way to start someone out with a big rifle. I was shooting some heavy cast loads with the 280 grain NOE 9.3 boolit in my 9.3x74 and slipped a round ball in while a buddy wasn't looking and handed him the rifle. Should have seen his face when the gun just kinda went pop. That same 3 gr load of 700x hits right to the same point as the heavy cast loads. I've also had fun with round balls in the 45-70.
So if you get bored or have a kid that wants to shoot your big boomer try out some round ball loads.....