AR10 bolt locking forward with dummy rounds

[Mr.Coffee]

So I have an AR10 80% that I built I have finally gotten everything together and working. I wanted to make sure that it would cycle rounds so I loaded a magazine with some snap caps (dummy rounds) pull the charging handle back and it loads the first round perfectly then i pull the charging handle back and let it go as fast as i can, the first round ejects and second round loads everything worked great. Then i try to pull the charging handle back one more time to clear the round and it wont budge. I did some research and found how to get the bolt unstuck by pulling the charging handle and slamming the stock against the ground. I'm not sure whats happening it looks like the bolt isn't returning to the proper position when the second round is pushed in. Is this something that will be rectified when i shoot live rounds? or is this a malfunction that I need to deal with beforehand?

[unforgiven]

If it's a collapsible stock unload,close the stock. If it an A2 type rifle stock, check for clear you can put a piece of wood on the ground. Grab the charging unlatched other hand on the handguard. Drive into the board sharply. Don't pinch your fingers 😉

[Albroswift]

I tap towards the rear on the charging handle with a small rubber mallet when I get one stuck. Haven't seen any detrimental effects from the procedure. Slamming the butt down does use the mass of the BCG to advantage but the little mallet doesn't frighten the other members at the range like banging the rifle up and down could.  

[unforgiven]

Hahaha bang the damn rifle. Hahaha

[DNP]

It’s called mortaring. You make it sound so cavemanish with the “banging”. It’s a technical procedure. You could always go Jim West style and bash it with a rock. 

[Mr.Coffee]

I guess i should've been more specific i am wondering WHY this is happening i already know how to fix it but why is it locking like this, is it because of the dummy rounds or an actual issue with my rifle?

[unforgiven]

When it happened to me it was with an empty case, locked up tight.

Rifle worked fine before and after.

[392heminut]

4 minutes ago, unforgiven said:

When it happened to me it was with an empty case, locked up tight.

Rifle worked fine before and after.

Empty case=fired case brother. If it wasn't resized yet that would explain that.

[unforgiven]

Exactly right expanded brass... that was my mistake. Got it on the second stroke  can't be shy or it ain't gonna happen.

[shooterrex]

Lube it up good and shoot it. My 2 pistols I built were like that for about 50 rounds. All good now.

[Sharpshooter]

Oooh, sounds like more lube is the answer to a lot of sticky issues!