I have am 1881 Springfield in 45-70 that I shoot and reload for.While at the range today I fired 20 shots and was getting my regular target when all of a sudden the shots started key holing 6 shots later I quit.Now i cast my bullets 405 grn sized to .458 and lubed ,I use 13 grns of Trail boss i do not use a card on top of the powder .All as I usually do but what the hell happend.The barrel wasnt even warm.There is definatly lead fowling in the bore and I am gettin rid of that now but what can I do to not have this happen again.Any one had this problem.