The ones I have experience with were heavier than you want, but had a very wide nose, they were 460 grain wide flat noses from Cast Performance. They chambered and worked perfectly in a Hunter model Contender. This bullet I believe is intended for lever guns, and the nose length isn't super long though. I would make up a dummy round with the bullet seated backwards, and seat it progressively shorter until you can fully chamber it every time. The length from the case mouth to the end of this backwards bullet will be the maximum length you can go to the radius on a wide flat nose. Hope this helps.