Great article. I won this exact rifle at a banquet about 2 years ago. I just installed a scope and shot it about a month ago and what a nice shooting rifle and extremely accurate with factory ammo. However, I did not have the same experience with Federal's ammo that you did. In fact of the three brands I tested in my XR100 the Federal shot the worst, Remington was the second best and the Hornady was the best. At 100 yds, I shot 1/4-1/2" groups from the Hornady ammunition and the Remington was around 1/2-3/4" and the Federal was 1/2-1"+. The Federal ammo just wasn't consistent for me. However, there are differences in every individual rifle and what works in one might not work in another so yours might just like the Federal loads better. I'm now working on a handload with 39gr bullets for the 204 with some good success under 1/2" so I hope to be seeing sub 1/4" groups soon.
I will say that I love this rifle and it's probably the prettiest rifle I own. I don't own many though!