i have built a lot of firearms to date, but never an ar. i finally got around to piecing together my colt ar15 kit, they were on the market a while back. it is build on a nodakspud receiver. the bolt seems to move freely on its own, but when i fire a round the round does not eject and basically jams the bolt, and to get the round to come out i had to the the side of the shooting bench on the charging handle. the fired round didnt looked deformed in any way. again this is my first ar build so any help here would be great. a also tried both steel and brass cased ammo.   thanks

Sounds like it's not getting gas from the barrel to pull the bolt back and eject the round/load another. Ensure your gas port on your gas block is lined up and that your gas tube is in correctly.

Have to ask. Is the gas tube installed? Canted, or blocked?

On an unloaded rifle you say bolt moves freely on repetitive dry firing?

Everything lubed up sufficiently, especially on a new build ?

it is all lubed, same as my factory bought ar's, and i followed build instructions to the t. after the round is fired, the bolt itself is so locked forward, i cannot pull it free by hand. i literally had to put the charging handle on the side of the shooting bench and hit the rear of the stock a few times to get it free. next round is the same story over and over.

Check your headspace.  Sounds like the chamber is tight...

You're doing that part wrong, you should be mortaring it open, if that's ever necessary again.  If you have a collapsing stock, collapse it all the way.  Always keep the muzzle in a safe direction, etc:

Pulling gently back on the charging handle with one hand, you lift the rifle and smack its buttstock on the bench or the ground from about six inches to a foot out, and the resulting force will generally free the stuck round.  You're not using too much force unless you're ripping the rims off the stuck cases.

I too would check the headspace...before firing it any more.
The symptoms you describe could be a lot of different things
to include improper headspace, which CAN be dangerous
if not corrected.

If you check and ensure it is not a headspace problem, then look at the DI (gas)
system as mentioned above for alignment.

Another person posted the exact same problem on another board.  I didn't think it would be the cause, but apparently, he wasn't getting any gas.  That is really easy to check.  Get a piece of 3/8 hose and hook it up to the gas tube in the upper and blow in it.  The tube will feel the tiniest bit restricted if it is normal, but if there is very little to no flow, you know you definitely have a problem.  The usual culprit is that people install the tube upside down, or they don't stick it in far enough before installed the roll pin, so the gas hole is not lined up with the hole in the block.

What ammo are u using 5.56 or .223 my buddy had the same problem he though he got a 5.56 barrel (but it was .223) so that what he was using it did the same thing I put some .223 in it never had any problem after that.

I am going to chime in and say headspace is probably the culprit here.  The bolt is getting locked and staying locked.  unless somehow the trigger is getting stuck on the bottom of the BCG which I doubt.  

I would check your gas block as well and make sure the set screws aren't lose and they are properly staked as well to keep them from coming out.  

I would have said gas until you described what you had to do the get the bolt back.  Sounds like the locking lugs are staying extra locked to me.  You probably just need a different bolt and not an entire bolt carrier group.  

But whats strange is you can cycle it fine without a round in...  Do you have any dummy 5.556//223 rounds?  Toss one in and see what happens.

That is almost exactly what I recommended to the other guy when he posted his problem.  I figured since his BCG was getting "stuck" it was a chamber problem.  Turned out he simply installed his gas tube incorrectly.  You have to keep in mind that brass expands and then contracts, but not all the way back to its original size, when it is fired.  That can easily account for having to drive the charging handle back that way.

Gas