Seating die problems-need input


Well-Known Member
May 9, 2001
I was loading up some ammo today and ran into some peculiar problems with seating depths.
I have a load worked up and had the die set from the previous loading. Die was screwed in all the way and the locking ring was tight. Dial indicator was in same position.
I loaded about 10 rounds, measuring each cartridge for over all length. Naturally, measuring from base of case to bullet ogive is what matters but it's not that easy to do so I measure to the tip of the bullet.
Anyways, the first 10 or so rounds measured out exactly where they were supposed to. Then, one round was about 8 thousandths longer. I didn't think much, figuring that the bullet itself must have a longer tip than the rest of the batch. The very next bullet though, was the same. I loaded about 8 more rounds and they were all 8 to 10 thousandths longer than the oal was supposed to be, and longer than the first 10 rounds that came out exactly right. These bullets were all from the same box and the die was locked in tight and did not move. Puzzled, I assumed the die had somehow moved internally so I adjusted the micrometer down .010 and reseated the last rounds. This time, they all came out the right length. From this point, I assumed that something must have moved internally in the die but that it was now corrected. If it was corrected however, and back to seating the bullets to the correct depth, I should be able to run one of the first 10 through (that were already to the right length) and it should NOT move them at all. I tried this and to my surprise, it seated them .010 under the desired oal. I assumed that this meant it was hitting the bullet ogive on the same point for all the rounds but that the last 10 bullets were about 10 thousandths longer???
I know this sounds confusing but I hope someone can offer some insight to this sporadic seating depth. The die is a Redding Competition with micrometer adjustment. Has anyone had problems with this die or do I have a batch of irregular bullets?
Thanks for any opinions you may have.
Measuring to the tip of the bullet from base (head) doesn't really matter only for feeding thru a magazine. The length from bearing surface to tips will vary quite a it. Measure 0'all seating depth from base to forward part of the bullet that is the full dia (30 cal @ .308", etc). Keep that measurement real close (.002"). Also you will usually have to change your seating depth on your seating die even with the same make, type and weight of bullets, they will vary, and of course other makes and types will vary greatly from the ones you commonly use. If you measure your bullets first before seating then adjust seating die slowly down to desired length (from base to orgive) you won't have any problems seating to optium depth.
I never readjust my seater after I determine they are all under the magazines OAL. If one is long, it's just that the tip is long, and sometimes that's longer than .015" even.

If you want to do it right, sort the bullets by length from base to ogive before starting. Shoot same length bullets in same groups. PSI would likely be more even and as a result velocity and trajectory also. How much of a differance it makes I don't know, never have done it to see, imagine I'll get to that sometime.
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