Good shooting.... IMI is typically pretty fast ammo, so combine that with good accuracy and you have a winner !

Most of my barrels have a decided preference between the 75gr Horn. or the 77gr Nosler / Sierra. ..... Only my Krieger is happy with either..... ( Slight edge accuracy wise to the 75gr Horn. )

Before you go and buy a bunch of 69gr ... I strongly suggest you shoot multiple 10 shot groups ( for accuracy ) in a row... IMHO the AR15 platform, being a high capacity, self loading rifle ( rapid fire ), you should test its accuracy for how it might be used.... heated up barrel, and slightly dirty....  

A hunting rifle with 3 shot groups from a cold bore is a decent representation of its expectations for accuracy..... but a self loading rifle is usually fired faster.

So .... test more ... 3 rounds from a AR isn't a good accuracy test  ( No Offense intended !! )

And if you spend much time at the 100yd line.... try Fed 50gr Tipped Varmint, cheaper then the more expensive match ammo, but still very accurate for its cost.


Also... while this may seem silly to some, I have noticed that some ammo needs a few rounds fired down the bore before its groups size settle down..... I haven't been able to quite nail down a exact trend.... but brand x followed by brand y might not give you a good sample.

Years ago I had a list from the CMP of "Which Powder should not be used after a different powder" for reloaded ammo.... but try as I may... I can't find it.  And bear in mind, that list was made from men with decades of "No Internet", real hands on experience.