Tried my hand at re-arranging things a bit.
Sherman Firefly Heavy Tank Patton/Rommel variant
Mass: 65 tons
Tech Base: Inner Sphere
Motive Type: Tracked
Rules Level: Experimental Tech
Era: All Eras (non-canon)
Tech Rating/Era Availability: E/X-X-E-A
Production Year: 0
Cost: 3,760,625 C-Bills
Battle Value: 1,117
Power Plant: 260 Fusion Engine
Cruise Speed: 43.2 km/h
Flanking Speed: 64.8 km/h
Armor: Heavy Ferro-Fibrous
Armament:
1 Plasma Rifle
1 Light PPC
1 SRM-4
2 Machine Guns
1 Vehicle Flamer
1 Unknown CASE
Manufacturer:
Primary Factory:
Communications System:
Targeting and Tracking System:
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Equipment Type Rating Mass
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Internal Structure: Standard 35 points 6.50
Engine: Fusion Engine 260 20.50
Cruise MP: 4
Flank MP: 6
Heat Sinks: Single Heat Sink 15 5.00
Control Equipment: 3.50
Lift Equipment: 0.00
Turret: 1.00
Armor: Heavy Ferro-Fibrous AV - 198 10.00
Armor
Factor
Front 50
Left/Right 40/40
Turret 40
Rear 28
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Equipment Location Heat Spaces Mass
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Machine Gun FR 0 1 0.50
Vehicle Flamer FR 3 1 0.50
SRM-4 FR 3 1 2.00
Plasma Rifle T 10 1 6.00
Machine Gun T 0 1 0.50
Light PPC T 5 1 3.00
CASE BD - 1 0.50
@MG (1/2) (100) BD - 0 0.50
@Plasma Rifle (30) BD - 0 3.00
@Vehicle Flamer (20) BD - 0 1.00
@SRM-4 (25) BD - 0 1.00
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 7 Points: 11
4t 3 3 1 0 3 0 Structure: 4
Special Abilities: CASE, TUR(2/2/1)
Dropped to 2x Mguns (half ton ammo), pulled one Flamer and changed the other to a Vehicle Flamer (1 ton ammo). Dropped one ML entirely and then stuck a LPPC in place of the other one. To make up for the range gap the LPPC creates up close, I added an SRM4 into the nose with room for 1 ton of ammo of choice (Inferno, Normal, or other). Finally, since the SRM ammo does create a minor worry about a bad hit wiping your unit, to say nothing of the Mgun ammo, I used CASE to protect everything.
Only being able to do 5 at 18 is meh at best, but at least it starts getting you into being to shoot something back at Clanners, and the range overlap works well with the Plasma Rifle's once you hit mid-range for both. On the other hand, only doing 5 damage at 18 means you'll actually get shot BACK at by Clanners that might normally ignore you. Your mileage may vary.
I'd have put the SRM4 in the turret, much like the Patton/Rommel's old LRM-5, but it would have gone a half ton overweight.
maxcarrion is still correct though, no matter how you cut it, if you want to have that Plasma Rifle AND have a substantial anti-infantry loadout together, you're looking at it just not being very combat efficient no matter what is added on, as there just isn't enough room to make it a viable anti-armor unit AND a viable anti-infantry unit. Just about the only way to get around this would be a LFE, but since you were going for low-cost, that isn't an option.