I was shooting a Savage 10 Tactical in 308 Win that was fully capable of sub MOA groups with 168gr match ammo. I tried Federal 180gr blue box in that rifle and got 12" groups at 100. Some ammo just doesn't work well with some rifles.
You can probably sell those 100gr Corelok loads to someone who has a stick that can shoot them tight. If nothing else take them to your local gunshow for trading stock.
Machine guns are awesome until you have to carry one.