Help my Grendel pistol isn’t accurate

[montana]

Here is something that isn't mentioned, nor have I mentioned on my builds....

Your bolt catch/release/bad lever is going to wear out the ears of the lower eventually.

I shimmed mine! I forget who sells shims for like $20 but a set of feeler gauges on Amazon is $6.

Make shims from feeler gauges, then it will have to chew through the shim first before damaging your lower receiver. I measured the gap, grabbed a feeler gauge that is 1/2 the value and then drilled 2 holes and cut it to fit with scissors. Fixture to hold down the shim was packing tape and a wood block.

https://triggershims.com/ar_15_shims.php#S25