I was thinking the same thing when reading through this post. In a tube fed levergun you are pushing one bullet into the other to "force" it into the tube. I have had 30/30 reloads without a crimp push the bullet into the case further thus increasing the pressure of the give round. Not only that, but accuracy is diminished from round to round as a result. So yes, for levergun ammo, I would advise crimping but for magazine ammo I wouldnt think that it is neccessary.