In the end I went for 4 small pop-up turrets each with a different option for a total of 1 ton and <KCr300.
AC-25 (Field Catalogue) with combat load, computer and smart tracker. (Range 2.5 Km | 9D damage | 100 Mag | AP 7 | Auto 3 | Blast 3)
Tac Launcher (CSC) with Armour Piercing Ammunition. (Range 6 Km | 8D damage | 4 Mag | AP 10 | Smart)
VRF Gauss Gun (CSC) with computer and smart tracker. (Range 750 m | 4D | 400 Mag | AP 5 | Auto 8 | No Signature)
CPPG-13 (CSC) with extended magazine (Range 500m | 1DD damage | 12 Mag | AP 10 | Blast 3).
Also helpfully P10 of the Field Catalogue provides information about firing in vacuum and no gravity. Each condition doubles extreme range. That gives an extreme range of 16 x the listed range which mean all but the CPPG-13 can reach into Short space range,
The Auto Cannon provides a reasonable short range effect against smaller ships as it averages 2 points damage per shot and full auto gives 3 chances. The Tac Launcher provides longer range softening up and some real anti armour capability. The VRF Gauss gun is designed to provide anti-boarding defence though as it can take specialised rifle ammunition there are opportunities to improve its anti-small ship potential for example, whilst TL16 Plasma rounds are 10 times the cost of ball ammunition they will add a dice of damage and double the AP to 10 making it much more effective against ships or more readily available APDS could entirely negate the toughness of the ship allowing the slightly reduce damage to have full effect. The CPPG range is not bad and it is the only weapon with destructive damage and a hefty AP. It is far more reasonably priced than the other plasma weapons and the extended magazine offsets the limited capacity.
Obviously all these weapons would be effective against ground targets.
I have assume any ship mounted weapons are effectively Vacuum modified (per the Field Catalogue).
AC-25 (Field Catalogue) with combat load, computer and smart tracker. (Range 2.5 Km | 9D damage | 100 Mag | AP 7 | Auto 3 | Blast 3)
Tac Launcher (CSC) with Armour Piercing Ammunition. (Range 6 Km | 8D damage | 4 Mag | AP 10 | Smart)
VRF Gauss Gun (CSC) with computer and smart tracker. (Range 750 m | 4D | 400 Mag | AP 5 | Auto 8 | No Signature)
CPPG-13 (CSC) with extended magazine (Range 500m | 1DD damage | 12 Mag | AP 10 | Blast 3).
Also helpfully P10 of the Field Catalogue provides information about firing in vacuum and no gravity. Each condition doubles extreme range. That gives an extreme range of 16 x the listed range which mean all but the CPPG-13 can reach into Short space range,
The Auto Cannon provides a reasonable short range effect against smaller ships as it averages 2 points damage per shot and full auto gives 3 chances. The Tac Launcher provides longer range softening up and some real anti armour capability. The VRF Gauss gun is designed to provide anti-boarding defence though as it can take specialised rifle ammunition there are opportunities to improve its anti-small ship potential for example, whilst TL16 Plasma rounds are 10 times the cost of ball ammunition they will add a dice of damage and double the AP to 10 making it much more effective against ships or more readily available APDS could entirely negate the toughness of the ship allowing the slightly reduce damage to have full effect. The CPPG range is not bad and it is the only weapon with destructive damage and a hefty AP. It is far more reasonably priced than the other plasma weapons and the extended magazine offsets the limited capacity.
Obviously all these weapons would be effective against ground targets.
I have assume any ship mounted weapons are effectively Vacuum modified (per the Field Catalogue).