Ballistic coefficient, and G1 vs G7
What a BC actually measures, why the same bullet has two different numbers, and when a G1 figure quietly stops being true.
The sound barrier and transonic instability
Why groups open up when a bullet slows through Mach 1, what the transonic band actually is, and why subsonic loads behave differently.
MOA, mrad and scope clicks
Exact definitions, the two shortcuts that are wrong, and how click rounding leaves a residual error you can calculate in advance.
Sectional density
Mass divided by frontal area — the part of the ballistic coefficient that comes from the bullet's proportions rather than its shape.
Bullet construction types
FMJ, soft point, hollow point, boat tail, open-tip match, monolithic — what the labels mean and which parts of them affect the flight path.
Twist rate basics
Why rifling is measured in inches per turn, how the Miller rule estimates whether a bullet will stabilise, and what over- and under-stabilisation do.