So, move it up to 16kg unloaded, then?
According to the 1200's fluff, the pulse rate was an artificial restriction they put in because it was draining regular power packs at an unacceptable rate. But if you move up to Satchel Batteries and Military Power Packs...
And I'm not all that fussed about the range, anyway. Remember that the SLDF, Comstar, and the Word of Blake all had uninterrupted access to lostech. Makes sense there's something in the Mauser internals that regular Pulse Laser Rifles can't replicate.
With all that in mind, here's the updated stats.
Armor Piercing/Base Damage: 4E/4B
Range: 45/100/250/625 meters
Power Points per Shot: 5
Cost/Reload: 8,000/*
Mass: 16kg
Notes: Burst 10; Recoil 0; Encumbering
The result is something like a laser version of a Portable Machine Gun. With a Military Power Pack, the soldier is hauling about 20kg of gear just for his gun. But his squadmates are sure gonna appreciate the withering hail of laser fire he can lay down.