I own a 1959 Win. Model 12 in 12ga. 28" Modified choke. The gun shop owner I bought the gun from is also my friend and has many years experience in gunsmithing. He told do not use any HTL shot because the barrels are much thinner than modern shotguns and using HTL COULD cause barrel damage. I took his advice and shoot only standard 2 3/4" Short Mag. lead in it. I would not use HTL in it but that is your decision. I know some fellows on here use it in vintage Model 12's but is it worth taking a chance? Take care Brother, from one who has traveled a bit and been to the East.