Bad Scope again!!?? Nope my fault

Well about three weeks ago I went to the range and my rifle shot 8 inches low, same ammo, no bumping scope nothing, no explanation, I couldn't trust scope so bought a new Nikon Monarch, 4x16x50. Zeroed it in nice. Took my dad for one last shoot this morning, Rifle shot about six inches low?? I put it in a vise, rifle shot five inches high, two bullets 3/4 inch apart. moved scope 20 clicks and shot again, two bullets 3/4 inch apart one inch from last group!! I was ready to throw the new Nikon Monarch and use it for a skeet target! Picked rifle up and in a bad mood shot four rapid fire off hand, all within an inch of the bulls eye! Handed my rifle to the range master, When he took it the forearm almost fell off!!! I think we found the problem, The bolt that runs down through the forearm had worked loose,,,very loose. Tightened that up and the rifle shot 2 foot high! Took a few rounds but doing real well now. Think a little locktight is in order. Hope I am the only one waisting ammo and money on scopes when the problem was in my left hand.