Armalite AR-10 w/20" stainless barrel free floated DD Lite Rail PRI front flip gas block-sight combo and FSC Flash/brake on the end.
This also has a Magpul AR-10 PRS GEN 2 stock. Upper is topped off with a Leupold MK4 4.5-14-50 Illuminated Mildot.
This combo of parts produces an honest sub 1/2" MOA groups all day long.
Here's the interesting part...... with the PRS installed using everything that MagPul includes (a shorter screw for attachment) the weapon stove pipes on almost every round fired.
With a standard Armalite A2 stock kit, it works perfectly every time!
Switch back to the PRS, and the stove pipes return..... back to the A2 and it works perfectly.
The PRS installs without any binding as it slips right on. The factory sling attachment loop is not too tight as it would be difficult to slide on the tube if it was.
What on earth can be wrong with the stock. and yes the drain hole in the PRS screw is drilled all the way through so that's not it.
As another effort, I have now moved this PRS to another of my AR-10 rifles..... a 16" target but have yet to get to my range for testing. Should know more this week.
Any input is appreciated.