Question: when did the army switch to the m4
[{'answer': '1994', 'provenance': [{'wikipedia_id': '321957', 'title': 'M4 carbine', 'start_paragraph_id': 7, 'start_character': 68, 'end_paragraph_id': 7, 'end_character': 72, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '321957', 'title': 'M4 carbine', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 778, 'bleu_score': 0.5677056834849601, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5756701514373838789}, 'section': 'Section::::History.\n'}]}]