I've often wondered about how well conicals fill the grooves when the rifle is fired. I think they do a pretty good job. Lead is pretty soft and when a rifle fires, the bullet is accelerated on the order of over 1000 g's. Thats alot of force. I would think more than a hammer blow. A hammer blow could do it so I suspect that the charge could also.

In my Sidekick, I got leading at 1550 fps and above with some conicals, for example, the 385 GP. The sidekick has deep grooves and they are cut. I figured that the rifling skinned the bullet as it expanded becauseit was accelerated down the bore so fast.

Of interest, my BPI rifles have shallow grooves and the grooves occupy twice the surface as the rifling does. This increases the shearing surface of the bullet (between each rifling) by 33%. The barrels are designed for the Powerbelt conical so I think it is intended to better grip highly acceleratedbore size conicals. The rifling is definitely cut, not buttoned.

For grins and giggles, I plan totest how patched roundballs shoot out this kind of barrel/rifling design. I haven't an opinion as to what the outcome will be, but will report what doeshappen when I test.