You need to remember a couple things. Many of the people who post here are flat out liars. They lie about what they own, they lie about their training, and most of all, they lie about what size groups they shoot.
Secondly, the majority of people here who are honest and talk about shooting MOA, are all using scopes. The amount of people who shoot 1" groups at 100 yards with a stock weapon aren't worth talking about. It can be done, but usually by olympic quality shooters (if they are getting an honest 1" at 100 yards on a regular basis).
I think your shooting is fine, and it will get better as you get more familiar with the weapon. With more trigger time, your 5 round groups will continue to shrink. Try to also remember that you have a combat weapon variant, not a tack driver. You can always build an accurate AR later on if that is what you are looking for.
Stickman speaketh the truth!
Practice, practice, practice. The A1's are capable of better accuracy than most shooters. Shooting is like golf and pool. The more you practice, the better you get.