the bestthing you can buy to improve the rifle is a box of bullets. then another box after you shoot the first one. then another box, and so on. it sounds like the set up isn't bad, so the best way to improve is to improve your shooting with lots of good practice.

as was said before, try some different types of ammo to see if the rifle likes any one kind over another. (all rifles will have a "favorite" ammo that they shoot more consistently well, and it is trial and error to find that kind for each rifle).

Another good idea to practice is to buy some snap caps. These are plastic fake cartridges that you load into the rifle and "shoot." What this does is get you used to squeezing the trigger smoothly and helps you avoid flinching as a reaction to pulling the trigger. Many people will flinch their upper body at the point of trigger pull because they are expecting to get hit with the recoil. This leads to pulling and missing shots. The snap caps allow you to dry fire (anywhere-basement, garage, etc.) with no blast to flinch for, so you get used to just squeezing the trigger and cycling the action, without bracing for the impact of the recoil. It may seem silly, but it absolutely works.

If you realy want to get deep into it, you can get the trigger adjusted to be about 3-3.5 pounds, or replace it with an aftermarket one, you can make sure the barrel is free floating so its not in contact with the stock, you can get a recoil pad to lessen the impact to your shoulder, thus decreasing the liklihood that you'll feel the need to flinch when shooting,you can get a barrel de-resonator todampen the barrel vibration,and more.

I'd spend my money on ammo and the snap caps.Mostly thereal shooting though.