Being that these where reloads, start by checking the spent primers in the spent cases to make sure that the loads are not going over pressure. Could be either reduced case volumes for the reloading data your using, or even OAL of the loads too long and you have bullet embedding on loading. Lastly here, make sure that you are working the loads up from the starting point of the data, and not just jumping to max powder levels instead.
Next would be to make sure that you have the chamber scrubbed clean via a chamber brush and CLP, are using a solvent to clean the rifle that is not leaving behind a residue like Hoppes does, and that you are lubing the bearing areas of the upper correctly with CLP.
From there, we get into the start check for spent dropped case from the bolt that do not clear the action,
Start with pulling the charging handle all the way back, and confirm that the face of the bolt stops about 1/8" to 1/4" in front of the back edge of the ejection port window. If the bolt is retracting back to far, you can pull the buffer and spring, and drop a quarter or two into the tube void to shim the end of tube forward.
Next pull the B/C, hook a spent case on the extractor and cam the eject into the bolt face a few times to make sure that the ejector is not binding in the channel for it. If the ejector checks out to move without binding, then pull the extractor and make sure that it bur free at the grabbing claw surface and the edges of the rim relief channel so the extractor is getting a good bite on the spent case rim.