MEXICO CITY (AP) — Two trailer loads of small-caliber ammunition bound for the United States were stolen by armed assailants on a highway in Mexico’s most violent state, Guanajuato, the manufacturer said Friday.

A company representative said about 98.5% of the millions of rounds of ammo stolen earlier this week were .22 caliber, which is seldom used by Mexican drug cartels.

“These will be of no use to them, given that they don’t use these weapons,” said security analyst Juan Ibarrola, who also acts as spokesman for the Tecnos Industries company

The .22 rounds are used mainly in rifles for target practice or extremely small game. Mexican cartels prefer larger, high-velocity ammunition for AK-47 and AR-15 rifles or 9 mm weapons.

The total quantity was not clear, but was estimated to be about 7 million rounds. The ammunition is sold in the United States under the Aguila brand.

Though low-powered, .22 ammunition can be lethal depending on where a person is hit, and from what range.

Mexico has also occasionally caught people selling improvised “pen” guns, single-shot devices disguised as pens that use .22 rounds.

The ammunition is made in Cuernavaca, a city just south of the capital, and was being taken north on trucks to the United States when the shipment was hijacked, The drivers were later found alive.