The M3 Carl Gustav is a good weapon, but I think an RPG configuration would be more useful. There is some prejudice in some US military circles against weapons with an exposed warhead, but in practice the warhead of a M72-type LAW is just as vulnerable to detonation by a sniper's bullet.
The Brunswick RAW (left) was an interesting weapon that showed considerable destructive potential. In form it was a spherical 140mm diameter rocket propelled rifle grenade. The original model had a 3lb (1.36kg) HESH warhead but in later models this was reduced to 1kg. This round could blow a 36cm (14") diameter hole in 20cm (8") of double reinforced concrete. A later development was MuliPurpose Munition or MPM-RAW, a pre-fragmented anti-personnel/anti-material round using tungsten pellets and know as the "Flying Claymore". This had five to ten times the effective range and lethality of a 40x46mm grenade and was fitted with a variable range and height-of-burst fusing for both direct fire and indirect fire to 2000m. Trials indicated 81% casualty hits out to at least a 35m radius. MPM-RAW also retained 90% of the breaching capability of the HESH-RAW. There was also a version with a HEAT warhead with a laser proximity fuse designed to detonate the round at correct standoff distance. The large 40 cubic inch capacity of the warhead could also be used to carry useful loads of fillings such as smoke, CS or incendiary compounds.