Colonial rules

[Aethelwulf]

What rulesets for around 40 miniatures per side, do you chaps recommend?

[italwars]

You 're talking, from my point of view, of a moderate Skirmish type action..
welll.. it's sooo easy to answer you:

  " The Sword And The Flame"  ! What else ? 

[EnclavedMicrostate]

Depends on period I suppose. The Men Who Would Be Kings is normally designed for an 'imperial' army of about 50 men versus a 'native' force of about 60-100 (depending on whether it's more of a fire-centric army like Afghans or Egyptians or a shock-centric one like Zulus or Mahdists), but the rules offer a 'Skirmish Kings' variant where you halve all unit sizes but leave all the other rules unchanged. For my part, I suspect that since most unit sizes are multiples of four that you could split the difference and reduce unit sizes by a quarter. So in other words, Skirmish Kings would see 25-ish 'imperial' versus 30-50 'native' troops; splitting the difference gives you about 40 versus 50-80.

Alternatively, there's a Sharp Practice variant for the Sudan that appears in Lard Magazine 2021 which you might want to have a look at. I personally have sort of gone off Sharp Practice for anything post-1815, but the rules variants for late 19th century models have got me tempted to give them another go for my Boshin War games.

[SteveBurt]

Blood & Steel from Firelock games are quite good. Better than their pirate rules Blood & Plunder (the initiative system is cleaner), and the hidden objectives work well.

[TWD]

Given the asymmetric nature of this type of warfare you'd generally expect the "imperial" forces to be about half the size of their opponents in number to give a reasonably balanced game. Equally sized forces would result in the superior firepower and discipline of the trained "imperial" forces winning easily.
So if you want 40 on one side you're probably looking at either 20 or 80 on the other

The Men Who Would Be Kings gives a good game. As someone above notes at the suggested size (24 points) your "non-imperial" forces are a bit bigger than 40 a side, but it works with smaller forces (or half sized units).

The Sword and the Flame is also pitched at the scale you are looking for - it is charming, but (to me at least) very dated and the combat in particular is fiddly - it was written more than 40 years ago and games and gaming mechanics have moved on since then.