Try here: youtube.com/watch?v=A2yrPUOPUj4

Yes, the charging handle on an AR-12 should be fully seated and flush with the upper receiver when the bolt is in battery (fully closed). A gap indicates a potential issue that needs to be addressed for safe and reliable operation.
Potential Issues and Troubleshooting
If your charging handle does not go all the way in, the most common reasons relate to the alignment and movement of the bolt carrier group (BCG) and the charging handle itself.
Bolt Not Fully Forward: The charging handle's function is to pull the BCG to the rear; the buffer spring then pushes it forward into battery. If the bolt is not fully closed (in battery), the charging handle will not be able to seat correctly.
Improper Assembly: The gas key on top of the BCG must align and slide into the channel on the underside of the charging handle. If it's not correctly aligned during assembly, the charging handle won't seat.
Obstruction or Debris: Dirt, debris, or a misaligned gas tube can obstruct the movement of the charging handle or the BCG.
Tolerance Stacking/Incompatible Parts: While AR platform parts are generally standardized, some aftermarket or different-brand components might have slight variations (tolerance stacking) that cause a tight fit or prevent full closure.

Good evening to you!! The charging handle will need a sharp tap once lined up properly. Hope this is helpful. Have a good rest of your day.
🇺🇸🇺🇸 'Merica' 🇺🇸🇺🇸

Hi James and welcome. The charging handle will not seat all the way. Once lined up for insertion, a quick, sharp tap should seat it properly. Shown a little better starting around 5:20 here: --- youtube.com/watch?v=A2yrPUOPUj4 ------ Cheers and stay safe!