Cold Clean Bore
Also: CCB · First-round impact
The first shot from a clean, room-temperature barrel. Often prints slightly off from the established zero because the bore is dry of fouling.
A barrel’s first round after thorough cleaning frequently lands a fraction of an inch differently than subsequent rounds. Causes include carbon-free bore friction, slightly different barrel harmonics, and (sometimes) the first round’s bullet picking up fresh solvent residue.
Precision shooters often track CCB offset specifically. A half-mil low at 1,000 yards on a CCB might be normal for one rifle. Some prefer to fire a “fouling shot” before any consequential string to bring the bore to its working condition.