GeneralPanic said:
I read that Sassanid bowmen were also thought to be able to do this (loose 5 arrows in rapid fire, from horseback)
Quite likely, there is a longstanding continuity in Central Asian archery traditions.
...OK, this is a bit long, and I should point out I'm far more knowledgeable on Medieval Chinese archery than Islamic, but here you go....
Ghulams generally used a variety of different bows of the Turkish type, different bows for different purposes... and different draws for differing goals too.
Ranges of 800 metres were certainly possible with a turkish-type bow—but NEVER in combat (these distances were just attempted for sport distance-shooting). Arrows would actually be loosed in combat at a range at which they could almost be guaranteed to defeat armour (i.e. under c. 50 metres).
At the ranges that they were generally trained to loose at (even at the outer 30 metre point for charging archery) wearing any armour was a bit of a moot point—the arrows would punch through regardless.
It should be remembered that arrows shot from composite bows at close ranges were often perfectly capable of "punching-through". There are even numerous reasonably modern examples of North American Plains Indians (although they used a weaker composite bow of a different construction), shooting straight through an adult female North American Bison and felling the calf on the other side.
As to accuracy, this would naturally increase when the archers sat on a stationary mount (as they were also trained to do), but
ghulams were typically aiming at the torso. However, as a charging
ghulam approached his target his accuracy would likely increase as the target grew closer in his view.
The arrows were typically "tanged" in construction (unlike the Western European practice of "socket" construction). "Tanged" arrows are somewhat weaker, and more prone to shaft shatter—but some break-up of arrows could be expected given the sheer impact forces involved (normally war-bows, such as the
'aqqar, were in the range of 50-75 kg draw weight).
and it is suggested they used a specific device to do it (but it is unknown what this was).
Of course arrows were not the only things that could be shot... with a bow called a
husban "grasshopper", fitted with a
nawak or a
majra arrow-guide, short darts, stones, and ceramic grenades of
naft "Greek-fire" could also be launched.
Many of the times
ghulams were defeated by Frankish forces were in fact due to poor "on the fly" organisation, and more indulgence in politicking than in the training that they should have been doing. Actually the sheer effectiveness (and status) of the Turkish bow could be seen as being a problem, its' continued use (well into the mid 18th C) being held by some as possibly holding back the military use of modern hand-guns in Ottoman forces.
I hope that this that helpful? However, as I mentioned, I know a great deal more on Chinese rather than Islamic archery—so I might be simplifying things.