Not taking anything away from SEAL shooters, but given a 25 yard target, that's really not that hard to hit. To add to Nate's thread, a 1 shot 1 kill with an M107 isn't an easy task by any means. So far, an Army scout sniper holds the furthest distance kill with an M107 and it was something around the 2,400-2,700 meter range. The Canadians used a TAC-50, that had a previous record.
See why .50 isn't the smartest thing for anything that short
http://airbornecombatengineer.typepad.com/photos/weapons_fireams/ptblkrangeillus460ace_1.jpg