One gauge. An entire family of cartridges.
Know exactly how far you’re moving the case shoulder during resizing. The Sigma8 Shoulder Bump Gauge helps you set your sizing die and maintain a consistent shoulder bump from case to case.
Unlike cartridge-specific gauges, Sigma8 gauges are selected by shoulder angle. That means one gauge can cover several cartridges. For example, the 20° gauge works with .308 Win, .243 Win, 7mm-08, .260 Rem, and .338 Federal.
Each standalone gauge is machined from passivated 416 stainless steel and works with the optional Sigma8 caliper adapter. Available in eight shoulder angles from 17.5° through 40°.
Fits cartridges up to and including .338 caliber. Shooting .358 or larger? Send us an email to request a gauge that works with your cartridge.
Important: For wildcat or improved cartridges, check your chamber print to confirm the correct shoulder angle before ordering.
Choose Your Shoulder Angle
17.5° Shoulder Gauge
Classic Springfield-family and long-action hunting cartridges with a 17.5° shoulder.
Common examples: .30-06 Springfield, .25-06 Remington, .270 Winchester, .280 Remington.
20° Shoulder Gauge
.308 Winchester-family and related short-action cartridges with a 20° shoulder.
Common examples: .308 Winchester, .243 Winchester, 7mm-08 Remington, .260 Remington, .338 Federal.
23° Shoulder Gauge
.223 / 5.56-family cartridges and related small-frame rifle cartridges with a 23° shoulder.
Common examples: .223 Remington, 5.56 NATO, .300 Blackout.
25° Shoulder Gauge
Common belted magnum hunting cartridges with a 25° shoulder.
Common examples: 7mm Remington Magnum, .300 Winchester Magnum.
28° Shoulder Gauge
Varmint and medium-capacity cartridges using a 28° shoulder.
Common example: .22-250 Remington.
30° Shoulder Gauge
Creedmoor, BR, and select magnum families using a 30° shoulder.
Common examples: 6.5 Creedmoor, 6mm Creedmoor, 6mm BR, Remington Ultra Magnum family.
35° Shoulder Gauge
Modern hunting and short-magnum cartridges using a 35° shoulder.
Common example: 6.8 Western. Also verify other modern short-magnum cartridges by published shoulder angle before selecting this gauge.
40° Shoulder Gauge
Steep-shoulder improved, competition, and custom cartridges using a 40° shoulder.
Common examples: 6 Dasher, 6BRA, and many improved or wildcat cartridges. Always verify the exact shoulder angle on custom chambers before ordering.