just my .02 cents,
from being a cannon cocker for one year {in the nasty guard} (between stints as a huey crewchief)
1) the safety officer at each firing point is supposed to check the numbers cranked into the gun by the crew, prior to pulling the rope
2) the army uses RAP (rocket assisted rounds) to gain distance to their 155's
3) yes, people have fired outside the range limits lots of times. happened at camp roberts one year; impacted near a roadside park on hwy 101
4) last time I drove thru the training area at ft. hood, they had billboard sized signs warning of overhead fire from points outside the impact area (got whizzed then)
5) the noise inside a self propelled howitzer (when firing) is nothing compared to outside
6) if the forward observer does not see the round impact, he is supposed to call a cease fire. this happened to our battery once.
on our gun, we fired 3 round in 45 seconds one time (on a priority fire mission-hand rammed)
being a redleg for a year was a blast. but I missed my hot showers while in the field.