[timb99]

0.035 is the difference between the barrel bore diameter and the choke constriction diameter.

The fact that it measures 0.707 means that it is made for a barrel with a 0.742 bore diameter, which is quite a bit larger than standard (12 gauge is nominally 0.729")

Do you know what your barrel bore diameter is?

 

[6541]

Ed:

Another way to think about it is the .035 represents 35 points of constriction with each point equal to .001".

Each point of constriction then represents an internal diameter change of minus .001" from the diameter of the normal bore. A standard 12 gauge bore is .729". However, the current trend is to provide overbored 12 gauge barrels which are larger than .729" so as to reduce recoil and improve patterns.

Ed Ward

 

[edthearcher]

thanks guys I knew you would come threw ED