BROWNSVILLE — A “suspicious object protruding from the brush” in Starr County led Border Patrol agents to a weapons cache that included an AK-47, three M4-style assault rifles, hand grenades, military-style uniforms and other related items, Customs and Border Protection said Monday. The seizure occurred Friday on the banks of the Rio Grande near Fronton, a small community about five miles west of Roma. Agents reported finding the four rifles, two hand grenades, a ballistic vest, two ammunition-carrying vests, three two-way radios, two uniforms, and 16 fully-loaded 30-round magazines. All weapons except the grenades were turned over to Immigration and...