Finnish forces used field artillery as AT with some succes in winterwar,and that was not direct but indirect fire.Here is a llink.At the bottom of the page is a paragraph of Soviet tank losses at Karelian Isthmus,there is stated that Finnish artillery destroyed total of 955 tanks.At the time the main caliber of Finnish artillery was 76mm .If you scroll down the page there is another less sophisticated method to immobilize tanks.Here is a picture of this mighty weapon.