Northag vehicle stats

Hi
Can any one explain why some of the british vehicles stats appear to be wrong or not in date. Firstly the year given for the rules is 83, the stillbrew armour didn't materialise till 86 ish. The second thing that comes to my attention is the number of swing fire a striker has compared to the 438 . The former only has 5 missiles even though it carried 10 and the 438 has 7.surley it is wrong to give the striker less shots.

Centurion and T-55 would be useful for second line units, also - why have an armour table with penetration 10 on it when there are no penetration 10 weapons? Given time period if the 120mm L55 isn't the heavy hitter what is?

Also noticed the ammo on SAM systems is iffy - SA-9 and 11 get 4 shots, 4 missiles in racks - fair enough, Tracked Rapier has 8 missiles and gets 4 shots.

Just had a look over a range of modern rule sets from very old WRG, TTG, GDW, CWC and others I've collected over a few decades and this is the first set I've seen that has no attention to rules for enhanced armour vs HEAT/HESH etc. or separate ammo types either, abstraction is fine but it's a pretty key element of the cold war battlefield otherwise why was it developed?