Centurion, Chieftain & Challenger gun info

[Mark Heaps]

Rather than replying on Stephen´s wonderful Centurion thread and maybe distracting from it or possibly causing offence, I have started a new one.

"Jump" had nothing to do with the angular displacement of the gun to facilitate the required ballistic trajectory for the projectile to hit the target. It was a natural & individual characteristic of each barrel due to the rifling and how it bit in to the driving band prior to the projectile leaving the barrel.
Boresighting, aligning the sights to the gun could be carried out perfectly, but some barrels would consistently hit either high or low, or left or right due to this "jump".

The CABF shoot, Confirmation of Accuracy By Firing, served several purposes. Primary intention was to give the crew confidence in their tank and it would hit where intended if they did their drills correctly.

If the impacts were too widely dispersed, then it was something for REME to investigate, find the fault & fix. Long hours for us but we wanted the crews to have the best tank we could give them so they were out there between the enemy and us.

If the rounds were impacting close enough together but offset from center of target, we could calculate what entry needed to be made in the Fire Control Computer to compensate for it, and the gunner knew what manual offset to apply should he lose the use of the FCC, which he would on the ranges as shoots became progressively harder with less systems available to him. Simulating possible battle damage and fighting on with what is available.

Sometime before I left the Army in early 2007, a Boresight for the IW ( also known as SA80 ) was introduced that enabled sights to be aligned to the barrel. A confirmatory shoot at the start of the range package was carried out and sights adjusted as required before the test shoots began.

Mark