My bolt is not closing/locking up reliably when loading a round. This sometimes is just a matter of using the forward assist to close the bolt the final 1/4 inch  or the round not being stripped completely out of the mag and everything stopping.  

I have a RRA A2 complete upper.  I purchased 3 different types of magazines and was having the problem primarily with one British 30 rounder, so I am guessing it is the main problem.(It is a very loose, sloppy fit vertically and front to back)  However, if I pull the charging handle and release it manually (not  pressing the bolt release lever and letting it snap- I'm assuming that's not a good practice), the bolt doesn't always lock up even when not loading a round.  So it makes me wonder if it could be more than the magazine causing the Fail to feed/go into battery.

The bolt is very tight inside the carrier.


So my question is, is it possibly the new bolt/carrier combination that will take a couple hundred rounds to loosen up?  Or is the buffer not providing enough return tension?  Or just the magazine catching the rounds and holding them a little too tight(doesn't explain why bolt won't consistenetly lock up without any magazine or round present)?

As a clarification, once the first round was loaded and fired, it was less of a problem with subsequent rounds.  

When cocking/charging the rifle, you should pull all the way back on the charging handle, and then release it to allow the B/C to snap back under it's own power.  This will allow the bolt/carrier to strip the round from the mag, lock the bolt, and lock the charging handle back into the upper.  If you are riding the handle forward, the bolt lacks the power to strip the round and lock.

Also, since the rifle is still new/tight, make sure that all the upper bearing surfaces are lighlty lubed with CLP.  This will allow the carrier to overcome the rough bearing surfaces until the upper breaks in (self polishes).

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Now on to groping the rifle:

As for the carrier/bolt/upper, shotgun the upper/lower open, stick your finger inside the carrier and pull back. There should be a little tension as the bolt cams out of the barrel extension (lugs), then it should slide back the rest of the way smoothly (to the back of the charging handle).  Slowly (using your finder still inside the carrier) glide the carrier back down into the upper. The carrier should glide down, with the bolt and barrel extension aligned (look inside the bottom of the upper), then there should be a little tension as the bolt re-cams back into the barrel extension.  

On the way back:

If the carrier is not freely gliding back after bolt unlocks, you need to check the four bearing corner of the carrier key to make sure there is not a bur catching the upper key slot on the way back.  

On the way forward:

If the bolt gets almost all the way to the barrel extension (lugs) and binds, then the gas tube is not aligned with the carrier key. To fix this, pull the hand guards, and slightly bend the gas tube at the middle of the barrel to get it into the correct alignment with the key.
If the bolt gets to the barrel lugs, but the bolt/barrel lugs does not align, the barrel will need to be re-set (if the rear sight is close to centered and the rifle is zeroed).

If everything feel correct, tilt the muzzle down (45*), pull the carrier back by your finger again and let it drop on it's own power.  The B/C should free drop, lock, and slightly bounce back off the barrel extension.

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Now if the upper checks out, it's time to check the lower.  

Note: When you check the lower, you will do as follows with the trigger at rest for a few times, and the trigger pulled back for a few times.  

With the upper on the lower relocked, slowly pull back on the charging handle, then ride it back down with no mag in the rifle.  

On the way back, you should feel the bolt unlock (cam out), then a slight free run, and then pick up tension as the carrier start to lower/cock the hammer.  At hammer pick up threw the end of cock, the tension should be constant, not harder at the very end of charging.  If this is happening, especially when the trigger is held back, then the hammer tail (where it contacts the disconnector behind the sear/hook) is too long and will need to be relieved by .040.

On the charging handle slow ride forward, If the carrier sticks about half way forward, then the hammer is catching the firing pin, and you will need to lower the top edge of the hammer to allow it to glide past the firing pin.  

If the bolt gets almost the way forward to the barrel extension (lugs) and stops, then the gas tube is out of alignment and you will need to realign the gas tube with the carrier key.

As for the bolt locking up when you are riding the cocking handle back down, on a new rifle, the bolt is still tight in the barrel extension, and you will need to use the FA to lock it (or just bump the butt stock).

Hope this helps.

P.S. You forgot to tell us what lower is on the rifle.

very nice dano523!  This one should be tacked.

Ok, two things you mentioned...

The bolt is very tight in the carrier.  It does not slide freely... it's not hard, but it's far from free.  I have lubed it and will assume that will break in with use. (?)

I removed the bolt and checked carrier movement.  There is quite a bit of friction as gas tube and carrier connect.  They appear to be lined up correctly, as I can apply pressure  in any direction and this takes it out of alignment and makes it worse.  The end of the gas tube is very shiny, so there is no doubt, contact/rubbing going on there.  Would it be sensible to shoot another couple hundred rounds and see fi it loosens up before getting real worried? (60 rounds fired so far)

Also, I have read that at 45 degrees, the bolt should close freely.  If I am understanding that right.  

When I try that test it closes to the last 1/4 inch.  If I make a steeper angle (like 60 degrees) it closes all the way.  

Sounds like the rifle is just still new/tight. Just remember to keep it lubed, including the bolt and carrier inners.

On the gas tube to carrier "Key", there will be a bit of friction as they mate, so they sound fine too. The true test is not with your finger, but with the buffer applying pressure.

And last, but not least, the drop test.  As long as the carrier in not binding up in the upper, it doesn't really matter what the angle the upper is held. The idea is to merely allow the carrier to move in the upper, and see if there is conflict.

P.S. What do you have against the Leisure Suit Larry game, or was it before your time?

Not before my time. Played it in college.

Thanks for the help.  I wanted to make sure it was just tight and not something out of spec.