A quick guide on obtaining the "Take The Bull By The Horns" Achievement.
How to Obtain Take The Bull By The Horns Achievement
To earn the "The Take The Bull By The Horns" achievement you need to ram (and hit) a Warlord with the Ram skill, who is, at the same time using the Ram skill against you.
First, you need the Ram skill, if you don't have this, speak to the Quatermaster at the Gladiatrix near Concorde to respec and change your skills to obtain the Ram skill.
Second, your Ram skill must be no higher than level 4, it doesn't have to be level 4, although it's best that it is, but it should be no higher than 4 or you won't get the achievement. The reason being the Ram skill adds a stun effect at level 5, as such if you try to ram a Warmaster with a level 5+ Ram skill, when you hit them you stun them and it no longer registers that you were being rammed by them, when you rammed them, and so the achievement doesn't pop*.
I tried to earn this achievement numerous times with my Ram skill at level 9 and just could get it to pop, so many thanks Sindri.
Third, we need to find a Warmaster that uses the Ram skill...
If you are just starting the game the dev claims you can earn this achievement on mission 4. In this mission you have to go to a waypoint at Edea and "destroy the escort ships", at this location you will find Ben'sara (a level 12 Vanguard Class Warlord in a frigate) and 3 other ships. Destroy the three ships and Ben'sara will flee, you then have to follow her "into the junkyard".
Once you catch up with her, a conversation ensues, at the end of this conversation, select the Fight option, NOT the Diplomacy option (the outcome is the same, with one option she gives up without a fight, the other she gives up once you bloody her nose) and as soon as the discussion closes, Ram her and the achievement should pop. Please note that this is all according to the Dev, I have not personally tried this option.
If you have completed the story, your next option for a target are Bounties, all of them are Warlords, but only those that are Vanguard class will use the Ram skill against you. Thus far I have only found one that does, although I am far from completing the game and will add others should I find them.
The one I have found thus far is William "The Bill" Mason, found near Nyx.
I found his lackeys south west of his location, once you have his marker on the map, park your fleet and approach him solo. Subspace to within 12,000 clicks and then drop to half speed. As soon as you reach approx 5,000 clicks he uses the Ram skill against you and as soon as you see the ominous orange glow of him using his Ram skill against you, click your Ram skill button. As long as your Ram skill is level 4 or under you should get the achievement first time.
If you make a mistake or accidentally tried using with a Ram skill above level 4, subspace away to just over 30,000 clicks and the Warlord disappears from your radar, resetting the encounter. Turn around and subspace back to within 12,000 clicks and try again, as long as you move at least 30,000 clicks away, the encounter will reset and he will try to ram you again as soon as you close within 5,000 clicks. If you make a mistake and do not reset the encounter he won't try to ram you a second time.
If you have killed William "The Bill" Mason, you'll have to hope one of the other Bounties you find is Vanguard class, it's also entirely plausible that a Bounty Warlord Class may be randomised, if so the info provided above for dealing with William "The Bill" Mason, will apply to obtaining the achievement with any Vanguard class Warlord.
If I happen to find any other Bounties that make use of the Ram skill, I'll update this guide, but this is all I have to offer for the moment.