In a process for priming ammunition casings (1) comprising a bottom (2) connected to a cylindrical side wall (3) by an annular flange (4) defining within the casing an annular throat (5) adapted to receive a pyrotechnic priming composition (6), the process comprising depositing on the bottom of the casing said composition (6), then introducing said composition (6) into said throat (5);
- the improvement comprising introducing said composition into said throat (5) by subjecting the composition (6) disposed on the bottom (2) of the casing to a progressive compression in an oblique direction (D) relative to the axis (X-X') of the casing and directed toward the throat (5), this progressive oblique compression being created by means of a surface (8), without a sharp angle and which is eccentric relative to said axis (X-X') of the casing, which is caused to turn about said axis (X-X').