Start with the basic,

Step one, make to correctly clean the rifle, including scrubbing the chamber with a chamber brush and CLP by hand, then to correctly lube the upper receiver bearing areas with CLP as well.  And again, do not screw up this step, hence make sure that the rifle has been correctly cleaned and lubed before it fired, and for this one cleaning, Just CLP used to both clean and lube the rifle (read next cleaning, you can throw some Sweets copper solvent into the mix to clean just the barrel bore of copper fouling, but still use the chamber brush and CLP to clean the chamber each cleaning).

Here if you need to learn how far to break the rifle down to clean it, and how to clean and lube the parts correctly if the rig did not come with a owners manual,
http://www.ar15.com/forums/f_3/7_Maintenance_andamp__Cleaning.html


With bolt in hand, cam a spent case off the extractor and make sure that the extractor is moving in and out of the bolt face channel without any binding (just a hell of lot of spring tension through),  While you have the bolt in hand, pull the extractor and make sure that it clean, including the channel under it (read make sure that you have pulled the B/C down to cleaning level and cleaned it as well).

With just the carrier and key (bolt still off the carrier), dry fit the carrier to the upper receiver with the charging handle locked home (will have to unlock it to get the carrier in first) and make sure that the key is not binding on the upper channel, and when the carrier get about a inch before touching the face of the barrel extension, can feel if the gas tube is correctly indexed with the carrier key as well.


Now with the B/C back together, drop it pack on the upper, lock the upper to the lower, then pull all the way back on the charging handle and look at position of the front of the bolt to the back edge of the ejection port window.  The face of the bolt should stop 1/8" to 1/4" in front of the back of ejection port window edge.  If the front bolt face is even with the back edge of the ejection port window, or behind it, pull the buffer and buffer spring, and start dropping quarters down the tube to use as end of tube spacers to short the void of the tube to get the bolt to stop the needed distance in front of the ejection port window back edge.
Note here, the buffer weights you are stating is for a telescoping butt stock receiver extension.  If you have a fixed stock, then you have the wrong length buffer in play.  As for the spring, telescoping butt stock spring should be around 10.5: and not the 11.75", which is for  the longer fixed stock receiver extension.

Now with all this checked, and the rig correctly cleaned and lubed, time for the range.

Load only a single round into a mag, insert the mag into the well, charge the round will leaving the empty mag in the well, and fire the round for effect.  The correct effect, the bolt locks back on the bolt catch. Since you have some other types of ammo, do the test with these as well.

If the bolt is locking back on all the ammo tested single round mag feed and fired, then load up some mags and go to town to see if the stove piping is still happening.  
If you do run into problems with the rifle not firing rounds, then you need to take a close look at the front of the carrier against the back of the barrel extension through the ejection port window.  If the face of the carrier is not hard against the back face of the barrel extension  when a round is charged, then the Firing pin is being block from reaching the primer and is a fail safe in the design to prevent a round from being fired when the bolt is not fully locked up.  If you run into this, then most likely that the ammo was not full sized correctly, and an ammo problem alone.
Note, when you charge a round, do not walk the charging handle back forward, just pull the charging handle all the way back and let it go so the bolt can strip a round out of the mag and have enough steam left to correctly lock the bolt up with the round chambered.  If you are getting back feeds with a know good mag, then we need a photo of the barrel feed ramps of the barrel in your receiver.



If the bolt is not locking back, then problem with rig that we need to dive into further, since could be a gas leak or blockage the problem as hand instead.  On this, need to check the gas tube to the FSB and the FSB to the barrel for leaks, as well as checking to make sure that that bottom of the key is not leaking against the top of the carrier.