The gun probably does not fit you correctly. Mounting the gun and shooting at a pattern board will help you determine your point of impact. If the gun came with shims then you can change the shims to correct your point of impact. If the gun does not have shims available, since you mentioned the old gun, then stock bending is an option. Also, a consistent mount is a must. Once you correct the gun fit you also should practice your gun mount. During the season I generally practice my mount 50 times per night when time permits. Since you are pretty much starting from scratch a few shooting lessons would be money very well spent. Your shooting issues can be caused by a few problems that we here could not determine without seeing you shoot. You could be lifting your head, your mount could be incorrect, you could be stopping your swing or you might not be getting the gun out in front of the target just to name a few possibilities. Thus, two or three lessons could solve your problem. A good shooting instructor can help you solve issues that you did not know existed. Good Luck.