pamtnman,
You should be able to safely use any diameter bullet that will easily fit into the unsized neck of a case fired in that rifle. If the case can't expand to release the bullet, pressure will go up, but if the bullet is able to move before it enters the rifling, pressure won't go up significantly. This is true even for jacketed bullets and lead bullets are even less critical. I regularly shoot .321" bullete in a rifle with .318" groove diameter and .364" bullets in a 9.3x72R with .358" groove diameter. By the time a bullet has traveled it's length in the barrel, it has been sized to fit. I don't think you would be limited to the smallest dimension of the oval bore.
Mike
Mike,
You don't think this because you did not spend two years trying to make the Lancaster oval bore shoot right. The question of bullet fit in the oval bore is not about pressure, but accuracy. Everyone before thought just like you do now, and they tried to make the oval bore shoot like you say it should here, and they failed. We now know that the Lancaster oval bore shoots a bullet smaller than the muzzle diameters. On the older tapered barrels, the bullet is almost ridiculously small. Do not ask me how this works, do not ask me why this is, I cannot tell you. I can only tell you that this is exactly how the Lancaster oval bore rifling works. If you don't like it, I don't blame you. It is contrary to every rule of ballistics etc et al ad nauseum. If you want to see all the work I put into this, the DGJ published three articles in 2017-2018 about it.
It is so irksome that my cut-and-dry little recipe for success on this new rifle is not working out. I am pretty sure I know why, and the ball is rolling to get it working right. I do appreciate your help with the bulletectomy...
