I bought a savage 110 308 and have had it out twice trying to get it sighted in. It came with a vortex scope already installed on it and I had it bore sighted at the store where I bought it. Every time I adjust the scope it will hold for 1 or 2 shots and then it's way off. I have tried 2 different brands of ammo and same thing. Is my scope trash or maybe a little loose or what else could it be