Sorry for the delayed response time to your question, Bill. Its the day job, ya know ;-)
On the obturation remark, it had to do with that old Nemesis, AKA 'Blooper', that hollow fonky sound that tells you the wad took a nap rather than fulfilling its intended purpose .. figuratively speaking, of course. In fact, I attributed the something less than a bang to the bbl's modified configuration, a combination of longer cones and bigger bore. Never chrono'd any of them. Could have I guess, but didn't feel the need or see the point. Would suspect their velocities would have been a lot more than 35 fps off, tho that's obviously speculative on my part. Hope this helps clarify my earlier remark about card, felt & mono wad obturation experiences, with that particular gun. No other 20 that I have had or have does the fonky sound ritual with any of those older wads.
John, I don't have a Becker 20, but wouldn't mind a remedy for that disparity, at the right price ;-)
