30 CFR 56.6304 - Primer protection.
(b) Rigid cartridges of explosives or blasting agents that are 4 inches (100 millimeters) in diameter or larger shall not be dropped on the primer except where the blasthole contains sufficient depth of water to protect the primer from impact. Slit packages of prill, water gel, or emulsions are not considered rigid cartridges and may be drop loaded.
Title 30 published on 2013-07-01
no entries appear in the Federal Register after this date.