When I was in Nebraska, the local SO where I worked had gotten M16A1's and had very little money to work with. I recommended Magpul MOE rifle-length handguards to mount lights to: https://www.magpul.com/products/moe-...length-ar15-m4
At the time I recommended whatever budget combo light/mount that IWC had going at the time. Today I would suggest a Magpul mount with the Streamlight Rail Light.
The Sully stock would be a good option: http://www.thedefensiveedge.com/Sull..._p/sully01.htm