Will the complete bolt carrier assembly lock into battery with no round or empty casing in the chamber?  If it won't lock into battery on an empty chamber, then try just the bolt carrier (no bolt, cam, or firing pin assembly) to see if it will go forward all the way into the upper receiver and mate correctly with the gas tube.  

If the complete bolt carrier assembly will lock into battery with no round or empty casing in the chamber, then it could possibly be related to the chamber, extractor and/or ejector.  Try checking the ejector for function by using a hard object like a punch to push on it.  The ejector should sit just below flush with the front or the bolt lug face, so if you push on the ejector with a punch, you should be able to get the ejector to compress rearward into the bolt and it should compress below the bolt face.

If the ejector seems to have proper movement, then it could be related to the extractor.  Try removing the extractor from the bolt, put the bolt (no extractor) back into the bolt carrier along with can and firing pin assembly, and then try to get the bolt carrier assembly (no extractor) to lock into battery on an empty chamber.  It it will lock into battery with no extractor, then you may have either have a bad extractor or the extractor doesn't have enough movement where the cartridge can get under it (possibly too much spring tension).  

Another check to put just the bolt assembly (bolt with extractor & ejector) in your hands, and try pushing an empty casing squarely into the bolt face, trying to get the extractor to open up enough so the empty casing will slide under it like it would when under the normal conditions of the gun cycling.  If you cannot get the empty casing behind the extractor, then you may either have a bad extractor or possibly too much tension.  

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123

Spent case will have expanded slightly larger than the chamber when fired and live cycled out, so it should always be a no-go trying to shove it back in the chamber.

As for the spent case, not only does is need to be full sized (use an ammo gauge to make sure that you have the sizer set correctly to fully resize the case to be begin with), but the case may need to be trimmed as well.


I bring this up, since with spent cases, it sounds like it cycles factory ammo fine, and now just a mater of figuring out why you not resizing the spent case correctly, or still need to be trimmed.

Also to point out, on the top of the ammo gauge, you have the high and low surfaces.  The correctly sized case should have the face of the rim/back of round surface below the top surface, but above the lower surfaces.  So this is your starting point when using the gauge,


The inside the gauge is the end of chamber cut, and this will tell you if the case is too long and needs to be trimmed as well.

Need a photo of the extractor installed on the bolt.
Hence enough that I can see the top of entry taper on the extractor that the case rim has to ride down as it pushes the extractor open during lock up, as well as the height of the bottom rim releif channel surface against the bolt face (to confirm that there is enough room for the rim to slip in to the claw once the extractor goes to snap back over  the rim during the feed.

Something like this with enough lighting is perfect.




Also, make sure that the large end of the extractor spring has been snapped into the extractor channel for it, and you do not have an O ring around the outside of the spring.
Note: may need to use a set of pliers to get the spring coil seated correctly in the extractor channel for it.