Most reloaders do not crimp rifle ammo unless it will be used in a tubular magazine or perhaps in a semiauto rifle. The crimp keeps the bullet from being shoved deeper into the case due to spring pressure in the tube magazine or the violent shove it gets into the feed ramp on an auto.
Crimping is generally necessary for revolver rounds for two reasons, first, to keep the bullets from coming out of the case during recoil of another round being fired and possibly jamming the cylinder, and second, for more consistent ignition of the powder charge and better accuracy. A proper crimp on ammo for a semiauto pistol keeps the bullet from being driven into the case during feeding and also makes feeding smoother in general.
A medium crimp is appropriate for most loads. A firmer crimp is needed for heavier loads. Most revolver ammo is loaded using a roll crimp, and most ammo for semiautos is done using a taper crimp. The roll crimp folds the end of the case into the crimp groove on the bullet, and the taper crimp squeezes the case walls down so that they grip the bullet more tioghtly, without folding the end of the case. You can use a taper crimp on bullets that don't have a crimp groove.
You can do an good job with the crimp feature of your seating die, but many of us nut jobs who are really serious about this stuff prefer to get a separate crimp die, such as the Lee Factory Crimp Die. It works well and allows you the satisfaction of having more stuff on your loading bench.
Crimping is generally necessary for revolver rounds for two reasons, first, to keep the bullets from coming out of the case during recoil of another round being fired and possibly jamming the cylinder, and second, for more consistent ignition of the powder charge and better accuracy. A proper crimp on ammo for a semiauto pistol keeps the bullet from being driven into the case during feeding and also makes feeding smoother in general.
A medium crimp is appropriate for most loads. A firmer crimp is needed for heavier loads. Most revolver ammo is loaded using a roll crimp, and most ammo for semiautos is done using a taper crimp. The roll crimp folds the end of the case into the crimp groove on the bullet, and the taper crimp squeezes the case walls down so that they grip the bullet more tioghtly, without folding the end of the case. You can use a taper crimp on bullets that don't have a crimp groove.
You can do an good job with the crimp feature of your seating die, but many of us nut jobs who are really serious about this stuff prefer to get a separate crimp die, such as the Lee Factory Crimp Die. It works well and allows you the satisfaction of having more stuff on your loading bench.