I dont have the American, but I have had better luck with the 140s in my bolt.
The last box I shot four five round groups of fgmm 140 and they averaged 0.72in.
Lots of people have good luck with the ELDs but my rifle likes the SMKs better.
That rifle is currently getting 0.60 average with handloads. But I'm still working on the progression.
I would buy a box of fgmm, a box of berger 140 hybrids, and some Eld 140s. One of those three should give you good results.