Look on the front of the barrel on the bottom below the sights. If it has a star stamped on it. Then it is a 4 grove barrel with a faster twist rate. The rear peep sight in it makes it much easier to pick up the sights.
Oh and if it is a star stamped barrel add 200 to 400 dollars to the value of the rifle. Star barrels are rare but not unheard of.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.