Beams only

[Stardust (OP)]

I see two primary weaknesses of this design.

first is range.  Given the tech level of your other components, 192kkm beam range is rather short.  A 256kkm fire control is within your reach, although this could easily be handled via a refit.

Second is dat MSP. The damn thing might break on the way to its assigned sector or on the way back.  I would sacrifice an armor layer or some of the fuel to add additional engineering spaces.

My unimaginative scientists have been chided and have been tasked with improving the range of our laser weaponry.

These 1st generation warships are meant only for local defense of systems that contain colonies able to maintain and resupply them.  With that said, I don't doubt that it's meager MSP allotment will create some problems until addressed.

Still not convinced about that weaponry, not just the FC aspects.
Using 4x4 Meson Cannons 'mostly for point defence' is suspect when Railguns are so efficient on a moderately fast ship. Little or no additional research is required, and volume of fire instead of high tracking speed means we don't need sophisticated fire controls to be effective.

4x4 Meson Cannons make more sense as general purpose weapons - only mediocre point defence, but reliable damage dealers. But that's tricky too, as then we need to consider synergy with our long-ranged weapons.
If someone crosses into Meson Range, our firepower is split between medium-sized lasers that'll scratch the paint badly but can't be expected to burn through defences in a single shot, and peashooters that ignore defences.
This is wasteful. Equal-sized laser turrets would take better advantage of existing armour damage, and have considerably longer range so we could slave them to the long-range fire control for enhanced capabilities at range. Since unturreted and turreted guns are only one size apart and the larger cannons have the same RoF with your capacitor tech, unifying everything including fire control would be better still.

Getting truly long range with Mesons is expensive and we don't gain damage potential in the bargain. Fitting lasers to a primarily-Meson ship for cheap shots is fine in principle, but I struggle to find an implementation that wouldn't be better as something else.
I see the main appeal of Mesons mainly for things other than mainline combat vessels: fighters, fast snipers (especially against certain spoilers), support for boarding actions, PDCs where other beam weapons would be ineffective...

*

Whether the MSP situation is a problem depends on many details... as it is, it seems a serious limitation but not an unreasonable one given the intended use.

A missile research expert has finally joined our academic team so railguns may be an option in the near future.  Since I'm concentrating on defense at the moment, she's currently working on gauss cannon related research.

The meson cannons were chosen for a number of reasons.  I want to experiment with beam based weaponry and the expertise exists to do so.  They are more for additional offensive firepower, especially when multiple targets exist, than for missile defense at this time.  They can also be used for planetary defense.  Research into meson based fighters is in full swing and will likely be a focus in our tactical planning.

I really appreciate the feedback you all are providing.

[Iranon]

An entry-level 10cm Railgun with its associated power plant gets you 4 shots on 3.3HS with your current reactors, very respectable for point defence even without turrets.
The Gauss line has important options (turrets, reduced size), but for fast craft it needs serious research investment before it can compete. The improved accuracy is desirable, but the bulk from weapons (6HS), turret gear and faster-tracking fire control adds up. Reduced size eats into their accuracy advantage.

As usual, there are other considerations and I'm not arguing that prioritising Gauss weaponry is wrong... but I'd need a specific reason to go for Gauss from the start instead of fielding Railguns as a stop-gap until my Gauss tech is actually good.
Considerations between weapon lines don't remain the same: I see Railguns as the low-tech option for point defence, but the high-tech option for secondary artillery (more compact than an equivalent laser loadout, but requiring more research and throttled harder by capacitor tech. I don't like investing heavily into Railguns, too limited).

[Anarade Relle]

The meson cannons were chosen for a number of reasons.  I want to experiment with beam based weaponry and the expertise exists to do so.  They are more for additional offensive firepower, especially when multiple targets exist, than for missile defense at this time.  They can also be used for planetary defense.  Research into meson based fighters is in full swing and will likely be a focus in our tactical planning.

Getting some Meson capacity is also good for planetary point defence. PDC's armed with Meson's can defend your homeworld fairly well from missile attack.

[Stardust (OP)]

Getting some Meson capacity is also good for planetary point defence. PDC's armed with Meson's can defend your homeworld fairly well from missile attack.

Mesons will be the backbone of my planetary point defense.

The Adamant class replaces the meson point defense of the Tennessee classes with railguns.

Adamant class Cruiser    14,950 tons     509 Crew     4195.85 BP      TCS 299  TH 2362  EM 0
7899 km/s     Armour 15-54     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 5     PPV 106
Maint Life 1.12 Years     MSP 877    AFR 357%    IFR 5%    1YR 705    5YR 10574    Max Repair 590.625 MSP
Intended Deployment Time: 3 months    Spare Berths 0   

1181.25 EP Magnetic Fusion Drive (2)    Power 1181.25    Fuel Use 55.06%    Signature 1181.25    Exp 13%
Fuel Capacity 1,500,000 Litres    Range 32.8 billion km   (48 days at full power)

25cm C6 Ultraviolet Laser (7)    Range 256,000km     TS: 7899 km/s     Power 16-6     RM 4    ROF 15        16 16 16 16 12 10 9 8 7 6
12cm Railgun V3/C6 (10x4)    Range 60,000km     TS: 7899 km/s     Power 6-6     RM 3    ROF 5        2 2 2 1 1 1 0 0 0 0
Rail Targeting System S04 64-8000 (2)    Max Range: 128,000 km   TS: 8000 km/s     92 84 77 69 61 53 45 37 30 22
Laser Targeting System S08 128-8000 (1)    Max Range: 256,000 km   TS: 8000 km/s     96 92 88 84 80 77 73 69 65 61
Magnetic Confinement Fusion Reactor S.5 (21)     Total Power Output 105    Armour 0    Exp 5%

Missile Detection Processor MR2-R1 (1)     GPS 32     Range 2.6m km    MCR 279k km    Resolution 1
Active Search Sensor MR25-R100 (1)     GPS 5000     Range 25.0m km    Resolution 100

This design is classed as a Military Vessel for maintenance purposes

Sometimes I think that I still have no idea what I'm doing with regard to warship design.