A “big auger” is an old west term for a “big shot.” The term appears in western stories, such as those by Andy Adams (around 1900). A senator or governor or mayor or ranch owner might have been called a “big auger.”
   
   
(Oxford English Dictionary)
auger, n.
1. A carpenter’s tool for boring holes in wood, etc., having a long pointed shank with a cutting edge and a screw point, and a handle fixed at right angles to the top of the shank, by means of which the tool is worked round with both hands.
2. An instrument for boring in the soil or strata of the earth, having a stem which may be lengthened as the perforation extends.
3. ‘A large spiral bit used to mix a material and force it through a die (as in a brickmaking machine or a meat grinder); the rotating helical member of a screw conveyor’ (Webster 1961). Hence as v. trans., to convey by an auger. 
 
(Historical Dictionary of American Slang)
big auger n. West. an important person; BIG SHOT; boss.
1868 Galaxy 114: “A most agreeable summer resort,” begins Big-auger….No people outside State’s prison are hated more cordially and justly than the Bigaugers.
1903 A. Adams Log of a Cowboy 125: I can’t quite make out this other duck, but I reckon he’s some big auger—a senator or governor, maybe. Ibid. 135: It’s the easiest thing in the world for some big auger to sit in a hotel somewhere and direct the management of a herd.
1905 in A. Adams Chisholm Trail 130: The big augers of the outfit lived in Wichita, Kansas.
a1940 in Lanning & Lanning Texas Cowboys 5 [ref. to ca1880]: “Big auger,” “bull moose,” and similar terms were used when referring to the ranch owner.
1940 F. Hunt Trail from Tex. 183 [ref. to 1870’s] The big auger’d send this herd over Niagara it was in his way.
     
20 April 1859, Weekly Telegraph (Houston, TX), pg. 2:
WACO, April 13th, 1859.
(...)
He got a plethora of work—if the expression is pardonable—and to “sum up the whole bill,” he was as an old friend would say, “boring with a big auger.”
 
3 January 1865, M’Kean Miner (Smethport, PA), pg. 1, col. 6:
Not a great while ago, a Western landlord, somewhat noted for his blunders, took it into his head to get up a hall at his “tavern.” As he intended to do things up brown, and everything on the big auger plan, he fancied that a few “store fixens” would be a great addition to the bill of fare of pork and turkey.
 
Live Search Books
Cattle Brand
by Andy Adams
Boston, MA: Houghton, Mifflin and Company
1906
Pg. 121:
You may think different, but I’m not afraid of any man in your outfit, from the gimlet to the big auger.
   
Live Search Books
Jack Derringer: A Tale of Deep Water
by Basil Lubbock
London: John Murray
1906
Pg. 90:
“He’s a big auger, too ,way up on the trail.”