Storms, Builder,
The 'freckling' discoloration is what's left of an oxide layer that the rust left behind. This is what blueing and browning amount to. So, per the posts about 0000 steelwool not removing rust blue, you should expect that it won't remove the 'discoloration' from rust/freckling. You're going to have to cut thru the oxide (pretty hard stuff) to get rid of it.