I was sighting in new optics and placed a .223 boresighter in the chamber. Sent the bolt home. Sighted in sufficient to take to range. Cannot get action to open. Tried forward assist - nothing.
Any suggestions? Help!
The forward assist will not help you open the action and could create a worse situation by forcing a bad round or in this case the boresighter into the chamber.
Collapse the stock if it will, grab hold of the handguard with one hand and the charging handle with the other and slam the buttstock onto a hard surface. This is called “mortaring” and should free the boresighter by brute force.
Forward assist won’t help you get it open. It helps close the bolt, not open it.
Forgive me, I have never used a chamber bore sighter before but don’t you just put it in the bore and adjust your sights then remove it? Why did you “send the bolt home?”
I am assuming that you can’t get the BCG to come back using the charging handle. Did it go all the way into battery?
If it didn’t you should be able to push the boresighter out with a cleaning rod from the muzzle end. If the action locked in battery you should be able to take the upper off the lower and maybe get a better purchase on the underside of the carrier and push it back.
If I am guessing correctly the bore sighter wasn’t designed to have a AR BCG slam into the back of it and your extractor may have deformed it to the point that it jammed into the chamber and it is stuck.
Can you give more information?
Mortaring will work to. 
I agree. Mortating is the only solution I can think of. Doing so, it should extract right out and eject just like a regular casing. Are you sure you got the right size LBS?
I confess that, in addition to mortaring, I have on occasion pinched the charging handle release with one hand while tapping the other wing of the CH with a rubber mallet (or something). More damage risk with that approach, I suppose, although I’ve never had any damage.
Thanks - mortaring did the trick.
I have the same kind of LBS and I always put it completely into battery to sight in. That’s what the istructions say to do IOT get a proper bore sight. This has never happened to me though. 
Mortaring worked. Thanks. Why’d I send the bolt home? Force of habit I guess - by the time I realized how stupid a move that was, it was all over!
:lol:
We’ve all done our share. I know I have. 
My 1st response was to say mortar it but I didn’t know your experience level and when I have told new owners to do that before they get a real horrified look on their face that I am telling them to slam their new gun on the ground. So I was trying to give you a less “dynamic” means of removing it. :lol:
So you are supposed to put it in and close it up?
I didn’t know that, learn something new every day.
My bore sighting has always been clamping a gun in a vice and looking through the barrel at a spot and adjusting the crosshairs/rear rings to that spot.
Been to cheap to by a LBS.
After you got it out were you able to tell what caused the jam? Was the LBS deformed? Sounds like you know this now but in the future, drop in the LBS, point the muzzle down, grab the charging handle and slowly ride it in until closed. What brand LBS is it?
Why not just assemble the upper onto the lower without the BCG while using the LBS?
I, too am no stranger to that age old question, “Why in the @$*& did I do that?”
X2 on the visual bore site, usually within 3-4" at 100 yards
sounds like a cool tool to have though…
The LBS needs to be firmly seated in the chamber to ensure accuracy. The procedure is identical to chambering an empty shell. While you could pull the BCG, it’s an extra step that isn’t needed and allows a greater chance of inaccuracies to be introduced. I generally just clear the weapon, lock the BCG to the rear, point the muzzle down, drop in the LBS, and ride the bolt home. It takes about 5 seconds and the weapon can be handled normally, including muzzle up without fear that the LBS isn’t properly seated or will fall out if you raise the muzzle. The weapon can be cleared normally and can be ready for action in less than 5 seconds as well.