Overspray would be the primary contributor to the loss of staying power with my design for SGA. Every round that was already committed after your target died would be wasted. This can be mitigated with trigger discipline, you know, rewarding player skill. As for Strikes and the like, it would certainly be a very powerful and attractive option, but like other weapons, it would have a time and place. Were it truly unlimited or regenerating ammo, it would be unreasonable.