Longslides, long barrelled revolvers and bullpup longarms and SMGs are more inherently accurate (a longer barrel has more turns in the rifling and thus is more accurate) giving the effect of an extra phase of aim on all shots aimed for at least on phase (max aim bonus still applies).
EG: Tyrus pulls his Invigorator and aims for two phases. He fires on the third with a +3 modifier.
Any .50 (that's 12.7mm for SLA purists) pistol can fire AE rounds however if the gun is not built with AE rounds in mind then any misfire will completely destroy the gun and the hand(s) it is held in.
Magnetic Accelerators have a micro-fusion powerpack that must be changed or recharged every 50 shots. Replacement powerpacks cost 10c. The 3110 can be linked into the power supply of the user's power armour (200c of modifications are required) for effectively unlimited firing.