Aha. Good finds.
a) Very interesting article (the first one, that is...haven't had time to look at the second one yet) - although of course I they were only using simple stones, shame they didn't extend it with other types of projectile.
And interesting to see that Xenophon claimed exactly double the distance that Vegetius did, I always thought he was twice the author
(Or alternatively, we could use the line of argument used regarding length of pikes not being as much as is commonly believed, due to a "short Greek cubit". A bit of a laugh I think - but it is worth remembering that ancient authors didn't measure in ISO-approved metres, so there are some other assumptions being made somewhere that need to be borne in mind when comparing the numbers.)
I was a bit confused that they seemed to be trying to draw conclusions on use of slings fired from atop fortifications and downhill, but the tests as far as I can see were on level ground. I think I get it in the end. The results quoted are for level, and there is an additional assumption that when used "downhill" (as per their reference site) the achievable distance would double. (The lack of a range bonus for being uphill is something I miss in current rulesets - especially when you have the option of firing over friendly troops downhill in front of you.)
Some of their conclusions seem a bit weak, or perhaps not sufficiently explained: if the outer wall of the fort cannot be reliably cleared by slingers on the inner wall it hardly proves that slings would not have been useful in defending the fort at all! Surely you man the outer wall until it is about to be breached - or am I missing their point?
Demonstrating that adult males on average sling further than elderly females comes dangerously close to the category of stating-the-bleedin'-obvious!
b) I gathered that the ancient lead shots would have something sort of self-stabilising capability, but I'm still assuming not as much as can be achieved nowadays, and certainly less efficient in this regard than a dart or arrow.
It would be cool if somebody could produce really slo-mo capture of a slingshot in flight to show the effect in action, and see how long it takes to stabilise. (It's eye-opening to see how much flex there is in an arrow at release and just after.)
There are far too many articles on slinging.org to wade through right now

And some of the OTT hyperbole on the front page makes me take them slightly less than seriously. But the discussion on different styles is interesting, e.g.
http://slinging.org/index.php?page=slin ... vid-taylor