To make multiple weapons more efficent means that a combination of multiple weapon kinds shoud grant you a boost at a given range.
While a mono build could be superb at its special range - but less powerfull at any other:
Here is some I did a while ago:
You see the standard trapeze of MWO damage:
You see that 2 MLAS are more powerfull till ~ 330m at 40% of the weight and less heat as the ER-LLAS.
A combination of would work - (for example 2 ER-LLAS and 4 MLAS)
In the lower part you see some of my curves - including range characteristics of each weapon.
As for the MWO weapons the MLAS are more supperior over the Large Lasers at short range -but because of the range characteristcs the damage drops of quiete faster. Near 150m the LLAS is the better choice - that deal more damage as the ER-LLAS until 400m
That is only for lasers... you can think - that the MPLAS is more supperior to the MLAS at much shorter range - while the LPLAS would outgun the LLAS - but still there would be a small range bracket were it is less powerfull were the other weapon starts to become better.
So for example for a given weight and heat ratio those weapons deal at that range the most damage:
0-10m - SPLAS
10-20m - SLAS
20-40m - MG
40-90m - MPLAS
90-130m - SRM
130-160m - MLAS
150-200m - LPLAS
200-270m - PPC
....
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