Two ways to charge a round.

Pull the charging handle to lock the bolt on the bolt catch, push the charging handle forward to lock it home, insert a load mag, and hit the bolt catch allow the bolt to run home under full speed.


Or, install a loaded mag, pull the charging handle all the way back, then release the charging handle to allow the bolt to run full speed home, taking the charging handle with it to lock it up a well.

As for quick checks,

Pull the charging handle all way back, and make sure that the face of the bolt stops around 1/8" to 1/4" in front of the back edge of the ejection port window.  If the face of the bolt will not come back far enough of the last inch of CH pull is much harder than the pull from about half way back, then you used the wrong spring or buffer lengths, or you use the wrong (too long) buffer tube end screws, and it now protruding into the back void of the tube.

With the bolt locked back on the catch, work the charging handle back and forth by hand.  The bottom of the handle should not be binding on the top of the butt stock, and the handle should lock into place on the upper receiver without having to be forced to lock up.

Lastly here, shotgun the upper open, stick your finger in the back of the carrier, and work the carrier against the locked charging handle, and upper receiver to make sure that the key or cam pin is not binding against either.  Now pull the charging handle all the way back, and now push the carrier forward with the charging handle in tow.  The carrier should move as smoothly as when the charging handle was locked in place.

As for last  of quick checked, remove the bolt from the carrier and with only the carrier and key, dry fit these into the upper receiver to check for binding and even to confirm that the gas tube is correctly indexed with the carrier key.  On the mag release button, make sure that the threaded tip of the mag catch is flush with the top face of the mag release bottom.


Now for the mag to feed two rounds out at once on a single charge, it's screaming a problem with the mag.  When all else fails on a Mag pull mag, pull the mag apart, and clean all the parts with CLP.  On the follower, check the skirt for plastic over casting that my need to be removed so the mag follower is not binding in the inside of the mag.


And like always, make sure to correctly clean the rifle, including scrubbing the chamber with a chamber brush with CLP by hand, and then make sure that the upper bearing areas have been lubed with CLP (including the parts in side the receiver extension (buffer tube) such as the spring, the buffer and the inside of the tube.

What Greasing?????
This is a AR platform, not a M-14 or M1 Garand, and no where in any operator service manual does it state to use Grease on the AR rifle!!!!!!

With the exception of the barrel bore itself, where something like a good copper solvent like Sweets will remove the copper build up without the need of a lot scrubbing, the rifle should be cleaned, then lubed with CLP only.

Lock the bolt back, slide the charging handle forward just before it starts to lock up, and using your finger time, how much pressure does it take to lock the charging handle in place. If it take a lot of force, then double check the latching side of the upper receiver for binding marks of the charging handle latch binding against it.

Hence you should not have to use the CH charging handle latch pulled out by hand for the CH to lock in place forward instead.

Also, have you check for any binding yet, since if the rig will lock up fine on a feed from the bolt on the catch and it released, but not a full charging handle pull and it released, then its a glitch/binding in the charging handle instead.  Hence with the charging handle pull, the face of the bolt is acutally farther back then if just locked on the catch instead.

And loose the grease, and just use CLP to lube the rig.  With the gas tube system, the action of the AR gets fouling dirty fast and the grease will just collect the grease and retain it.  CLP on the other hand, had a cleaning agent in it, and will dissolve and flush the fouling out of the action before it can bind to the surfaces and choke the rig out  instead.