They are likely my fault somewhere along the line so don't rip me too bad but looking for suggestions.

1st up a 10mm AR pistol build. New Frontier Armory Large frame Glock lower with Spikes Tactical LPK and ALG trigger, Kaw Valley 10oz Tungsten buffer, and forget what spring. Upper is a Rainier upper, New Frontier Armory 40/10 BCG, with KAK Industries 7.5" barrel.

Charge the rifle and she chambers smooth as silk and fires a single round just as she should. The bolt extracts the empty brass but the brass does not eject it stays in the bolt and of course continues forward while the next round is loaded causing a nice little log jam.

So I am presuming there is an issue with the bolt/extractor. I had the issue every time. Using both Sig and Federal XM10 which both work just fine in the 10mm handguns.

2nd problemo .350 Legend SBR.
Anderson lower with a Colt LPK (this has worked just fine with other uppers). The upper is a brand new Bear Creek Arsenal 10.5 upper (yes, maybe the problem) using a .350 Legend specific 20 round Duramag and 145gr Winchester Ammo. So far these are the only mags and ammo I can get a hold of.
I am not sure if it is an Upper issue or a magazine issue. Pull the bolt back and let it go forward the bolt just skates right over top of the round most of the time never even grabbing the round but leaving a nice scratch in the brass.On occasion it will just start to grab the round at the rim but the bullet nowhere near raises up enough to even come close to chambering and the bolt just sticks with the round just slightly above the front magazine lip.

I did standard function checks and everything went smoothly but I have no 10mm or .350 Legend dummy rounds so I waited till I was at the range for a function test with live ammo and well here we are.