Excellent PDF from Berger on internal ballistics, addressing seating depth, COAL, and ogive positioning.
Effects of Cartridge Over All Length (COAL)
and Cartridge Base to Ogive (CBTO)
By: Bryan Litz
Many shooters are not aware of the dramatic effects that bullet
seating depth can have on the pressure and velocity generated by a
rifle cartridge. COAL is also a variable that can be used to fine tune
accuracy. It’s also an important consideration for rifles that need to feed
rounds through a magazine. In this chapter, we’ll explore the various
effects of COAL, and what choices a shooter can make to maximize the
effectiveness of their handloads.
COAL.pdf (2.0 MB)