Upper receiver help

About a year ago I bought a upper receiver and Handguard kid and I’m finally getting it all assembled. When I put the bolt in I notified that it was a tight fit. The bolt will almost lock into place but you have to press the forward assist to get it to lock. It will fire and eject but it will not load another round all the way in you have to hit the forward assist. I was thinking it might have something to do with the inside of my upper being cerokoted? If anyone has any suggestions it would be greatly appropriated!