Editor recommended because this is the officially named Prestige Attachment for M10 BREACHER. It is not labeled BEST. Tradeoffs are quoted from official launch copy.

M10 BREACHER
StockMFS XK-Lite StockReach maximum Weapon Level and Prestige the weapon.
One-of-a-kind stock that offers a strong improvement to sprinting and walking speed. Also improves dive and slide to fire and spread when diving, sliding, sprinting, and jumping. Harms damage range and charge time.
Attachments 1
- StockMFS XK-Lite StockReach maximum Weapon Level and Prestige the weapon.
One-of-a-kind stock that offers a strong improvement to sprinting and walking speed. Also improves dive and slide to fire and spread when diving, sliding, sprinting, and jumping. Harms damage range and charge time.
Alternatives
- Base weapon / no prestige attachmentKeep the base gunsmith path if you do not want the official prestige tradeoff quoted above.
Evidence basis: Source
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Recommended · bo7-m10-breacher-prestige-launch