Thanks guys, interesting explanations as to why the "step" is there. The greater the step i would guess the bigger the discepancy in actual to marked choke performance?
Sounds like some "jugging" is occuring with the design of these chokes, which is why the maths doesn't add up.
I would normally shoot UK 1/4 and 1/2 (US imp cyl and mod) on sporting clays, but from reading this would UK imp cyl and 3/8 (US skt and light mod) chokes equate more to this?
And for skeet, cylinder and cylinder seems the way to go?
Appreciating all you input.
That's about right.
It depends on the length of the choke 'leade' (for lack of a better word) as to how much jug effect you might observe.
Invector+ is a good sturdy system, at least the threads are not under the choke constriction like Beretta did with the Mobil Choke.
Not every mistake results in a blown barrel either. I once changed out a Beretta Optima choke at a sporting clays station, got distracted, and forgot to tighten it down. I shot 8 targets with it held in the barrel of the 391 by about 2 threads. No damage. My lucky day I guess.
Another time my shooting partner did the same thing with the choke just inserted and not threaded at all. I watched the choke sail off, kept my eye on it, and we walked right out and picked it up.
