New Grendel, dreaded fail to feed

[Sinclair]

Just got this upper. Barely anytime spent with it. Cleaned and oiled then 65 rounds in heavy crosswind.

Rifle buffer and Colt (I’m pretty sure) spring. Have not checked the port size, as this was a pre-built PSA.

I’m not in the same State as the gun most of the time so I can’t just play armorer at will.

Bummer, diffinetly hampers ones progress. I have found that just sitting and looking at the problem for awhile will sometimes bring about a solution. Sort of like Henry Jones in 'The Last Crusade'.