Hornady Steel Match is NOT generic ball ammo. While my handloads are all under 1 MOA for 5 shots, the Steel match is running about 1.5 MOA in my ARs and nothing worse than 2.2 MOA.
A mil-spec set of sights are going to open that up some until you have a lot of trigger time and learn the techniques. The top Iron sight shooters are using filed down, aftermarket or globe sights with precision inserts to increase the repeatabilty of the sighting system.
There are not a lot of people that can hold better than 1 MOA and few rifles that shoot better than 1 MOA. Add that together with stack-up and most people are going to be shooting 3 to 4 MOA for groups of 5 or more rounds.
You are doing fine for staritng out.