DMX, these models are indeed ridin dirty.
When I was filling out the force organization chart for my Vraksian Militia, I had a tough decision to make. While it would have been easy to run all three fast attack choices as Vendettas, I didn't want to go with a totally cheesy representation. While the Siege of Vraks books mention rough rider squads being used by the Death Korp of Krieg, I thought that the Vraksian Militia may have had some labor animals around that they too could have re-purposed. Also, Rough Riders are a nasty counter-charge unit, and fill a vital "rapid response" role in the IG battle plan. Seems like an easy choice! It's just too bad I won't get to convert any chaos Hellhounds.
The horses used on these models come from the Chaos Marauder Horseman kit, and feature a lightly armored, chaos embellished warhorse. This fit my needs quite well. Using this kit also had the added benefit of presenting a satisfactory lower-half of the rider. I needed legs that could be placed on the horse, but not represent an unbelievable "fantasy-style" set of armor. Using a modelling saw, I cut each rider at the waist, and pinned the Vraksian Militia torso in place. The Cadian "special weapon handle arm" made for a good choice here, as it allowed the riders to appear to be gripping their mounts, and also gives the mounts a bit of a Vraksian feel, with handles being implanted in their necks. Really, the only part of the model that took some work, were the explosive-tipped hunting lances.
According to the fluff, Rough Riders rush into combat holding a hunting spear, that has a bladed-tip packed with explosives for a one-time destructive charge. I like this idea, but I didn't think that a blade would really fit the industrial theme of a Vraksian Militia. To this end, I decided to tip my hunting lances with grenade-like explosives. First, I removed the hands from a variety of outstretched Cadian arms. Then, I pinned the Marauder Horsemen spear-holding hand to the wrist. After clipping the spearheads off of the Marauder Horsemen bit, I pinned an Ork stikkbomb to each shaft. These stikkbombs came from the Ork vehicle sprue, and in my opinion, form very satisfying explosive charges. I can certainly imagine my Rough Riders screaming into a close combat, directing their explosive-tipped lances at the enemy's faces, and detonating the charges.
I hope you like the finished product. I am tempted to build a transport superheavy, just so I can drive up and have my ten-man Rough Rider squad come charging out. Something about cavalry charging out of a tank seems so... unexpected.
Stay warm, all. It's getting too cold to prime!