Howdy
The power of the cartridge has nothing to do with what type of bullet to use in a lever gun. When each cartridge gets stripped out of the magazine, the magazine spring slams the rest of the column of cartridges backwards fast and hard. That is a when there is a danger of a pointed bullet firing the primer in the cartridge ahead of it.
Yes, always use flat nosed bullets in a lever gun with a tube feed. Take another look at the bullets in the photo of the cartridges I posted. In addition to Round Nosed Flat Point bullets, the Truncated Cone bullet works well on lever guns. Avoid anything with a sharp shoulder such as a Semi-Wadcutter.