question: What are the Colt model numbers of the models named GAU-5A/A, with no bayonet lug, no case deflector and stock of 2nd generation? 
answer: SELECT colt_model_no FROM table_12834315_1 WHERE bayonet_lug = "No" AND stock = "2nd Generation" AND case_deflector = "No" AND name = "GAU-5A/A"
context: CREATE TABLE table_12834315_1 (colt_model_no VARCHAR, name VARCHAR, case_deflector VARCHAR, bayonet_lug VARCHAR, stock VARCHAR)