Center to Center or Edge to Edge

[dmproske]

Typically when a person posts here and states "she grouped 3 into .5" at 100 yards" are they measuring Edge to Edge of the group or Center to Center of the outer bullet holes??

My simple redneck mind thought it made sense to measure edge to edge. Though I read that it is the norm to measure center to center....

[AJ Peacock]

The groups are normally listed as CTC (Center to Center). Normally they are measured Edge to Edge then the caliber is subtracted from the measurement. For example, if you shoot a .75" edge to edge group with a 30-06, the group would be .75-.308 for a group of .442"

AJ

[dmproske]

Thanks. I often wondered how in the world yall were getting those groups, thought they were edge to edge.