- Mar 6, 2008
This is a thread for discussion of the article, Effects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2, By Bryan Litz. Here you can ask questions or make comments about the article.The first half of this article focused on the importance of COAL in terms of SAAMI standards, magazine lengths, etc. There is another measure of length for loaded ammunition which is highly important to precision.
Refer back to Figure 2. Suppose the bullet was seated out of the case to the point where the base of the bullet's nose (ogive) just contacted the beginning of the riflings (the lands) when the bolt was closed. This bullet seating configuration is referred to as touching the lands, or touching the riflings and is a very important measurement to understand for precision handloading. Due to the complex dynamics of internal ballistics which happen in the blink of an eye, the distance a bullet moves out of the case before it engages the riflings is highly critical to precision potential. Therefore, in order to systematically optimize the precision of his handloads, it's critically important that the precision handloader understands how to alter bullet seating depth in relation to the riflings.