For example I can and have shot 1" groups and even a couple of times sub 1" groups from both an scoped MK-85 and a Rem 700. This said, I've also shot really terrible groups as much as 3-5" with the exact same everything (or so I thought) thanks to a flier or two or sometimes nothings seems to want to group.
And another man who is honest with himself with probably alot of experience we can learn from.
Tahqu, that 2.5MOA is with 100's of man hours finding the right combo too with all the different rifles.