Ever went to a reenactment, and tried to reload a musket while marching? Well... it's not easy, it's awkward as threading a needle in a strong wind.
The question is, could a snake with arms be better at it?
Note: By the advice of Green, I am posting two questions. One for Centaurs, and one for Naga. Here is the other question.
Can Humans reload while marching?
Yes, and seemingly in good time. This man managed to run at a good pace while reloading his musket in a reasonable time, 29 seconds to reload and shoot.
Note he is NOT using paper cartridges. His hope is to get his time down to under 20 seconds while running faster, which would put him well into the standard of 3 rounds a minute if he managed that.
Why would Naga be good at reloading while moving?
Surface contact with the ground. Snakes have many tiny legs under their scales, but effectively they have no legs. Their entire underside is always in contact with the ground, they don't have the jerky motion of a horse or human shifting their weight between steps. So, this sounds like a really stable position to work from?
Notably, when slithering, you do get some 90 degree turns periodically, forming the famous S-like shape of a slither. The naga likely will grow accustomed to these shifts in direction and naturally adapt to them, but it is a potential distraction. It is possible the greater length and girth of a naga over other snakes will make this process less frequent or more subtle.
Size and Weight of Naga
Naga might be anything from 9 feet long (including human torso) at the bare minimum, to 22 feet in length. They would also have substantial girth (probably two feet in diameter at the thickest point), so as to sufficiently move the human torso.
Based off those estimates, their weight is likely to be between 350 and 750 pounds, for a six-foot male turned naga.
Speed of Snakes
According to this BBC movie, Black Mamba snakes can travel with a third of their bodies raised at full speed (7mph long distance, with 14-20mph for short bursts of speed). Thanks to G0BLiN for finding this.
Naga, being larger, might be faster. However, they are not built purely for speed like the black mamba, and so will be slower than a comparably sized black mamba.
For speed in water, green anacondas move in the water at speeds up to 12mph. I could not find their land speed, as it seems there have been very poor and few attempts to record the speed of snakes.
What was the question, again?
Could Naga reload muskets while "marching" or "running"? And more specifically, could they do this more efficiently/effectively than humans?
The reason I am curious is if the answer is yes: then presumably this will be a key point in Naga military doctrine.