After rolling through the gates into the military base north of balota, my character stood up on his own, pulled out his AKM101 (Full attachments) and threw his weapon into the ground and the weapon permanently disappeared. I waited a while to see if it would reappeared for about 15 minutes. Nothing happened. I was rather disappointed as everything was pristine and I had no side arm.

Edit: This apparently can be repeated, as I lost my MP5 earlier doing virtually the same thing elsewhere. I strongly advice putting your weapon away before rolling into potentially hostile situations, as you may end up without a weapon.