Man, where to start?
OK,
[s]The firing pin can't touch the primer if the bolt is not locked.[/s]
[b]If the carrier is assembled correctly the firing pin can't touch the primer if the bolt is not locked.[/b]
Don't forget to install the cam pin when you reassemble your rifle.
Lots of guns can be reassembled with parts left over.
If you leave out the cam pin the carrier will come back independant of the bolt the instant that gas exits the gas tube. The initial high pressure gasses, combined with the lighter weight from lack of bolt, and the lack of the delay from unlocking will result in the carrier being shoved to the rear with much more force than normal. Quite often this damages the rifle. Not an "explosion" per se, but pretty catastrophic. I saw this happen on the range once with a brand new M16A2 and although I suspect the cam pin was missing I left the unit before the findings came back.
If the carrier comes back independant (lacking the cam pin) of the bolt the bolt will never unlock.
If the carrier never opens, aka the bolt never unlocks with a normal assembly, (for whatever reason but I can't see a practicable one) the gas tube would most likely split. I've seen it done with "restricted" gas tubes.