3 hours ago, Euphie said:

I don't want to be a complete geek here, but isn't this the Cerberus Harrier maybe?  A fully automatic version of the M-96 Mattock with slightly less impact but comparable accuracy and, unfortunately, also recoil? 

I suppose not, because the Harrier has a longer upper part than the Mattock, so we can assume that it's the M-96 with cutom Cerberus detailng

This is definitely the Mattock, lets pretend its Cerberus Black Ops Division custom AR, an element so secretive we haven't seen it in any game, but they were there xD 
Also I generally avoided automatic weapons unless the game difficulty was high or highest, prefering this rifle or the burst fire one you get from Archangel mission. 

21 hours ago, Euphie said:

Sure, I can pretend it, I like role-playing for better immersion  So we're talking about the period between ME2 and ME3 here, Cerberus is just starting field testing of the modifications to the M-96, which in the near future will result in the construction of the Harrier  Commander Shepard (let's assume he was a male) had copies of Mattock at his disposal aboard the Normandy SR-2, which he used with remarkable effectiveness during his mission before breaking contact with the organization. Cerberus engineers are interested in this old design and are working on improving it as we speak. Clear as a day for me 

Now change your name and hairstyle quick, you know too much there !