Original listing:

https://www.fire-support.co.uk/product/gp-m16a1--vn-stock

Was hoping to improve my E&C M16A1 with this purchase, but to fit it would've required chopping the attachment bolts so in the end I decided to stick with the E&C stock.  I did take the trapdoor butt plate from this set and it now has the E&C one, but that's the only change/usage.  Otherwise I just took it out the package, did a trial fitment, changed my mind then back in to the bag it went.

The great thing with this guy is that rather than the iffy super long single bolt going all the way from the butt plate to the lower receiver (as my E&C currently has), there's a far shorter screw that anchors whole thing right close to the base of the stock, then a totally separate little screw at the back which only holds on the butt plate.

Price is all-in.