shotgun measurment

[DanTorz]

Hi all could someone tell me the measurment of the land to land in millimeters, for a 12 gauge and an 18 and 20 guage. Thanks in advance

 

[guntech]

Hey Dan, what island are you on?

 

[guntech]

The bore diameter for a 12 gauge is .729"
The bore diameter for a 16 gauge is .667"
The bore diameter for a 20 gauge is .617"
The bore diameter for a 28 gauge is .550"

I have never seen an 18 gauge and have no specifications for one.

 

[Claybuster]

Guntechs numbers are the commonly accepted figures for shotgun gauges but there can be a great variance in the actual bore diameters. In 12 gauge I've owned factory guns with inner bore measuments ranging from .724 to .735. This potential variance means that measuring the bore at the muzzle doesn't always reveal choke constriction.