Seems like .310" is what I remember being the correct 30 Luger bore diameter. I think Hugh Clark has done tons of loading with the 30 Luger and would have a lot of info. Email him at
hhclark@wildblue.net or perhaps he will see this and respond. No, I did NOT have a way to chronograph that load but it was really accurate. I once popped a Pepsi can at 60 yard with a 30 Luger the first shot which is really beyond my eyes at present. I had a great rest and the 6" Barrel helped. I guess I just get lucky once in a while