Bullet Seating- Sloppy linkage & press spring can cause variation in the COL length. To remove this, a steel washer .061" thick & 1" in diameter is placed over the case onto the shell holder. On seating the bullet, this RCBS press will "cam over" removing any slop or spring coming from the press. No Crimping. Testing 223 & 55gr fmjbt shows a variance of .001" when taking the measurement off the ogive of the bullets. Lee's Dead Length Bullet Seating Die should do the same, because the bottom of the die contacts the shell holder.