Each one(prototype) that I've shortened so far has been done a little differently. I've now worked up a method that works well, but it requires a jig that I built, to guide a router bit on the inside of the stock to hollow it out further. I've also got another jig that aligns the stock in the saw to shorten it at the same angle as the A2 stock.
There are easier ways to do it (you could just chop it with any saw, hollow it out a tad with a Dremel tool, and epoxy the buttplate back on), but I'm working on a way that won't void the factory warranty whatsoever, and may eventually even be offered as a factory option. It allows the buttplate to mount exactly as it does on a standard length CAV-15, and not lose any structural rigidity at all.
"Cavalry Arms Custom Shop" has a certain ring to it.[:D]
I just need to find the time...
[url]www.cavalryarms.com[/url]