Measuring barrel lenght, how do I do it?

[chemo]

Okay I just edited my previous thread instead of creating another so disregard second post, it's not related


So my new question is: how do I measure barrel lenght for my shotty? From Benelli's website, lenghts should vary from 28'',26'' and 24'' But I see neither of these dimensions on my barrel

From my reading of second picture, the barrel lenght would be 27'' if measure from tip to end of the actual barrel. 27" is not a valid barrel lenght according to benelli's website

What's up with that?

 

[Big JD-From the hills]

I haven't looked that hard, but haven't spotted anything in canada. I was wanting a 4 shot extention for my 26"barrel.... but then the weight would likely be out front too much and light=quick. #4 buck is like death himself is dispensed for yotes within range, so I only need a few shots anyway(I don't hunt birds).

 

[chemo]

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