Originally Posted by RobF
What's different about the ostler stripper si? What does it do that others can't, and how?
Your asking the wrong person.
However, when "Jon" first saw it he said to me, "at last someone else has found out how to make one, i did that x years ago."
Ostler puts it down to the very small cone (4.8mm) and tight build tolerance in actually stripping the vast majority of air away.
I believe the design is also the result of much testing, hence Gillys mk1 was front vented only, current version is front and back.
I have no idea how far the cone is from barrel?
I know shooters like Challis who took his Aa stripper off noticed no difference with barrel only.