I'm going to expand it with a Ratling Squad and pad out the infantry platoons to be three squads each, in time. Meanwhile, there's a snippet more of the fluff. This section is taken from the background to 9th Battalion, my first army.
L U X I M P E R A T O R; 9th Battalion
It was alongside 8 Bn. that 9 Bn. was formed to bring the Praetorian Guard up to a regimental strength. In line with the general effort to include more light units, 9 Bn. was designated a light infantry reconnaissance unit, to conduct scouting raids deep into enemy territory. To this end, 9 Bn. were gifted fewer heavy armoured vehicles but their ranks received additional instruction in skirmish fighting: open order advances in open ground, and advances-by-section in urban or jungle areas. Emphasis was placed on personal martial skills such as marksmanship and fieldcraft.
Their first action was Kasr Lutien, M41, during the Black Crusade. The reconnaissances conducted provided information vital to the successful assault following a lengthy siege, in which the 9 Bn. also participated. In the nine-day engagement, the battalion was mentioned in planetary dispatches every day for its unwavering valour and fortitude. Following this successful campaign 9 Bn. worked in close concert with the Invidiae. Having been formed at the same time and since fought in the same engagements, these two are considered as ‘sister battalions’ and a strong martial bond exists despite their relative youth. Dropped by 8 Bn. landers, 9 Bn. operated behind the front line of Enemy troops, targeting isolated principalities corrupted by the enemy and engaging solitary outposts. Their exploits served to strike fear into the hearts of the enemy; captured heretic commander Zamrod admitted during questioning that, ‘we all feared the Ninth... every advance we made or attack we planned factored in interference from this battalion. We knew there was only a battalion, but at times it felt like there was a brigade loose behind our lines.’ 9 Bn. were later granted a signal honour when the Inquisition ordered his crucifixion to take place at their battalion headquarters. Since this campaign, they have acquired the Regimental sobriquet of the Lux Imperator; spreading the all-illuminating light of the Emperor into the darkest corners of the Enemy’s realm. They have, along with the other battalions of the Praetorian Guard, recently been engaged fighting on Edethor Luna where their actions continue to draw the highest praise upon the current battalion commander, Maj. Hadrius.