This is a mil-spec rifle with 4150 barrel and 1:9 twist which means that the temperatures and pressures generated pushing the bullet down the barrel will be less than a 1:7 or 1:8 twist and it will last longer. It should be happy with 55 to 62 grain bullets. It should give you 7000 rounds before it becomes a problem as long as you do not make a habit of sustained rapid fire. If you want to use it hard spend another $200 and get a chromed barrel for sure.