On the current retirement plan a federal employee would only receive 25% of the average of his high three years, and I'm not sure if you qualify for retirement that early. On the old retirement plan you would get 46.2%, but there are very few people left on that plan.
On the accelerated law enforcement scale 25 years would qualify for retirement at 39% of the high three years.
I have seen teacher retirement scales that hit 90% for 25 years of work, but not federal employees.
You are correct - most of the examples I have are of county & state employees, and of these I do know several who've retired on 90% of their highest salary.
However, I know a federal judge who's close to retirement, and according to her the figures I gave aren't far off.