Something does sound funky bud - I hate to say it. The internet isn't paying off much on this one either but I have found a couple of statements that, if I am reading your post correctly, lead me to my conclusion (which doesn't mean much!):
Taken from a website with the history of the M16:
The rifle will not fire unless the bolt is locked and the bolt carrier is in its forwardmost position. My A2 was the same way (obviously) Taken from here:
http://world.guns.ru/assault/as18-e.htm
Here is a link to an old TM for the A1 - page 22 describes the function check:
http://www.biggerhammer.net/manuals/...912/TMM16A.PDF
Still trying to find some answers.........
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FN Five Seven , USP Compact .40 , Sig Mosquito , SWR Warlock