Thank you for this! I had no idea that page in a different book was a key part of the FC process.
CSC uses a different rule. That said there is nothing stopping you using the special ammunition types there with custom guns from FC, just don't expect 1-1 correlation.
For example:
The GS-40 on p77 starts at Penetration 2 but looses a point because of the barrel length. P18 tells us that is AP 1 per full dice damage. The base damage is 3D so it becomes AP 3 and matches the description in CSC of the basic gauss pistol. So far so good.
The Navy version has a longer barrel and it retains the full penetration and again p18 tells us this is AP 1 + 1 per full dice of damage for a total of AP 4. The rule also says the damage should drop by a point, but...
Now you can use those guns with FC Armour-Piercing rounds which cost double and add +1 to the weapons baseline penetration.
The GS-40 Army now has the damage and AP of the Navy version with conventional rounds or AP 4 and damage 3D (-1 cough!)
The GS-40 Navy on the other hand becomes Penetration 3. This is AP 3 plus 3 per 2 full dice damage (for a total AP 6) with 3D-2 for damage.
Now you can also use those guns with FC Advanced Armour-Piercing rounds adding +2 to the guns baseline penetration.
The GS-40 Army now has the damage and AP of the Navy version with FC Armour-Piercing rounds (AP6 damage 3D-2).
The GS-40 Navy becomes Penetration 4. This is AP5 plus 2 per full dice damage (AP 11) with 3d-3 for damage.*
For the same cost you could use CSC Armour-Piercing rounds which have a slightly different effect. These simply add the number of full damage dice to the AP of the weapon and don't affect the damage it does.
The GS-40 Army would become AP6 damage 3D.
The GS-40 Navy would become AP7 damage 3D.
There isn't a contradiction as such as there are different performance trades are being made and Allah loves wondrous variety. The FC Advanced AP rounds in the GS-40 Army are worse in all regards than the generic CSC rounds, but you don't have to buy them.
I am happy that you can either get ammunition licenced by the weapon manufacturer that is matched to the weapon and get the FC results (maybe requiring a specialist supplier depending on the commonality of the weapon).
Alternatively you can buy the generic ammunition from any well provisioned star port and get the CSC results.
Real world ammunition for the same weapon has variation. Sometimes the manufacturers ammunition is for a particular application and sometimes it is another brand. Sometimes the manufacturers version is worse for every application, perhaps because they underpower their rounds to avoid potential litigation when the gun blows up or their through-life cost model was skewed to the in-service phase.
"Oh you were not using genuine Espon cartridges... sorry warranty voided."
You pay your money and make your choice.
* This is a stonking combination and probably a decent default carry. AP 11 is good enough to deal with the majority of readily available armour and can even start threatening some of the high grade stuff. 3d-3 is enough as it stands, but with the option to put another set into the same target without significant recoil makes it very respectable. Cr100 for 40 shots is hardly going to break the bank. The range is exceptional for a pistol and with the shoulder stock with built in scope you can credibly reach out to 200m and your target nit even know you are shooting at them until they are hit. ***** Would buy
