First, go buy a few different varieties of ammo for it. As said above, some rifles are picky. Don't overlook the cheap stuff either. My Savage shoots the cheap Winchester 150 gr Power Points into 3/4" all day. Rem 150 grain Core Locks average about 1.5-1.75". Same weight, same basic bullet shape, and roughly the same velocity, but one shoots far better than the other.

Secondly, what do you really expect from an inexpensive break action rifle? 3" groups aren't great, but they're not terrible, either. 3 MOA is a dead deer to 200 yards or a little more. So unless you're shooting farther than that, it will do ok. Most of the factory T/C Encores I've witnessed won't shoot sub-MOA. Those that do usually have aftermarket barrels and custom accurizing work done to get them there. But if you're going to give up hope after trying just one type of ammo, you're probably throwing your money away prematurely.

Mike