How Much Neck Contact
Date: Mar 22 2016
The amount of contact between case neck and bullet is critical to many loads. The old rule of thumb is that there should be around a bullet’s diameter of contact between the neck and the bullet’s shank, say about .25 inch for a .257 Roberts or .33 inch for a .338 Winchester Magnum.
That rule can be modified, however, depending on recoil level. With lighter-recoiling cartridges not nearly as much contact is needed. I’ve gotten fine results in .22 centerfires with not much more than .1 inch of contact, handy when shooting 40-grainbullets in the .223 or .22-250 Remingtons.
It also depends on whether the rifle is a repeater. One reason for sufficient neck contact is to prevent bullet shift during recoil, but if the rifle only holds one round, recoil can’t shift the bullets in the magazine. I’ve loaded bullets with much less than .375 inch of contact in a .375 H&H Ruger No. 1 with no problem.
If recoil is substantial in a repeater, however, there should be at least one caliber of contact, and sometimes more. This can make far more difference in making sure the bullet stays in place than a roll crimp. If you really have trouble keeping bullets in place during heavy recoil, you might eliminate use of the expander ball in your sizing die. This leaves the neck a little undersize, so it grips the bullet more firmly. Often a crimp isn’t even needed with this technique, though you must chamfer the neck sufficiently to allow bullet seating, unless, of course, you’re seating boat-tails.