Well just was sighting in my M14S today and figured I'd check out "the same ol' problem".
My M14S LOVES....168 HP ammo. From a good rest it'll put the American Eagle M1A ammo into 1" groups at 100 yards and 168 Federal Gold Medal Match into .75".
But it HATES......147/150 grain ball ammo. I've tried XM80, DAG, South African, no change, all grouped 8-10". Well today I figured I'd try out ZQI just for the heckuvit, don't have anything to lose. Did the same, maybe a shade worse.
Just boggles my mind. It's well headspaced, has a NOS USGI bolt that was installed by Tim at Warbirdscustomguns. It was WAY out of headspace before the new bolt was installed, swallowed a 7.62 Nato nogo gauge.
I just thought y'all may be interested. Like I said, even with a warm barrel, after 15-20 shots she still groups very well, but cold/whatever will NOT shoot 150 grain ammo.
Below group was prone @100 yards unsupported, however it was not me, the green group is 168 American Eagle and the red is 147 ZQI. The one far-right green was a called pull-off by me.
Edit P.S. Took off my Bushnell Elite fixed 10X scope and replaced it with a 3-9X Burris compact. Only 10" long and sure lightens up and trims up the gun.