Mark a cleaning rod with patch at the end of the muzzle.As you slowly push it in,the rod will turn with the rifling.When it has completed 1 turn,mark it again,remove the rod,and measure the distance between marks.This will be your rate of twist eg: 10 inches between marks= 1 in 10.You don't say HOW old this rifle is but if it is anything like my 110,the triggers are easily adjusted.If you are not sure about it though,take it to a gunsmith since a trigger that is set to light can lead to an accidental discharge.