bolt compatibility

[NugginFutz]

I have one of their side charging upper assemblies, in 5.56. The bolt and modified carrier both look very good. I see no blemishes, or sloppy tooling marks. I have no issues with these bolts or carriers, so I wouldn’t hesitate one minute ( other people’s experiences not withstanding.) My Grendel bolts fit quite well into this carrier, so I am contemplating building another Grendel as a side charger and keeping the 5.56 bolt as a spare.