well, I use ace mod and i can't get enough of the m-109, m-107 in appearance but using a 25mm high velocity explosive round. at long range just hitting a vehicle or getting close to a soldier will kill or seriously injure. at close range, trying to use the scope is useless but generally just firing randomly will get your target, it fires as quickly as a aa-12 with similar explosive effects but with far greater velocity and accuracy. thats generally paired with a submachine gun.
so bassically
M-109 w/6 magazines
mp-7 or mp-5 as backup