How is minimum OAL measured?

[Venom1956]

I was thinking last night at work about minimum OAL of rifles and shotguns and i had a question on it

after hours of painstaking work creating these visual aids.

Now the difference could be marginal but it could also be the difference between an ok gun and a not ok gun. I'd just like to get some more knowledgeable members opinions on this. (i just used the mossberg cuz it was easy to find and show my point)

 

[T. O'Heir]

It's the top one.

 

[4thPoint]

It's not the bottom one.

Things get marginally more complicated when you add in a folding or adjustable stock; Federally they are measured in the extended/unfolded position (again as in the top example) but two(?) states measure from the folded position.

 

[Snyper]

The proper way is to measure along the barrel axis.
The shortest measurement method is always the one that counts