I did read it. I have an LLB too.
I would argue that the hand wave here is that he draws the analogy with muzzle breaks - and insists that choke tubes be treated the same way. I'd love to see case law on that. Like a precedent.
Hmmmmm.
OK - so how many of you who have shotguns which can be fitted with choke tubes habitually fire them without?
Not having a muzzle break is the normal operating state of the rifle - being shot without a choke tube in place and breaking the threading at the end of your barrel is far from normal.
I think it is a weak parallel indeed.
Additionally he says that the bore is measured at the widest place in the barrel - maybe so.
So - how wide is the bore on a vented barrel? I would argue infinitely wide - my calipers can go all the way out to the whole rest of the universe if I want them to. Well that cant be a sensible interpretation.
Consequently it would seem that in interpreting this OIC you should take the ordinary and normal use of the words, subject to a reasonableness criteria.
Cant blame the guy for pointing out a potential extreme interpretation of the OIC - that's how he makes his living. But I think he's a long way from certain ground.
[to be clear though - neither he nor I are your lawyers - and you should act on neither piece of advice without getting external legal advice if you are worried]