Apologies for the necro, had a thought for LB-X pellets to make it a lower need for rolling locations:
The LB-X shot rolls normally on the cluster table to determine how many pellets hit the target. From there, you divide it into 4 pt groups, similar to LRMs. You then roll for the location.
On a Mech the damage is applied in the following order:
1st point) that location
2nd point) 1 section 'inwards' on the damage transfer diagram
3rd point) 1 section 'outwards' of the original hit location
If there are additional pts of damage remaining, go back to the 1st and repeat.
So a standard 4 pt hit on the left torso would apply 1 pt to the Left torso (this is also the only one that would get the potential for a through-armor crit), 1 pt to the center torso, 1 pt to the left arm, and the 4th pt to the left torso. If it is a hit on the leg, the first point damages the leg, the second hits the center torso, but the third has no 'outside' to go to. The damage starts back at the top by doing 1 pt of damage to the leg, and the 4th pellet does 1 pt to the center torso. (IIRC, excess damage to legs goes to the center torso instead of the side torso.)
(You would still get to roll normally on the crit table if the location has no armor.)
You would get fewer crits (approx 1/4), but the faster damage allocation means less need for a box-o-dice.
For vehicles, I'd want to make it where if a location receives 2+ pts of damage from pellet clusters it would roll for crits. So if the last cluster of pellets is only 1-2 pts, it will not cause a crit roll. The pellet clusters of 3-4 pellets will cause 1-2 crit rolls.