To close the loop on this: I sent an email to Piranha about this valve. I did not specifically say I was going to post their message, so I will only briefly summarize their reply.
My biggest reason for writing the email was to let them know about this issue. I assumed that they would have been unaware: it just seemed so unreasonable to me that they would sell a valve that was so clearly unable to perform the task it was designed for, and one where it is very easy to visually identify the problem simply with a glance once you know about it.
However, it seems that they *are* aware of this issue. They "have heard of some folks having issues and we got those back and are asking our valve guy to work on this for us." There were no other details regarding a specific solution, including timeline.
They also say they wished I would have contacted them before I machined them, but that it's too late now. I certainly considered that, but not least because of the inconvenience of the Piranha return process I decided to move forward the way I did. I don't fault them for not volunteering to take back my valves after I machined them. I certainly understood that possibility -- likelihood, really -- before I modified them.
I replied to them and asked more specifically what their solution would have been had I contacted them, and expressed my confusion why they either weren't setting aside the valves with the large and easy-to-see shoulder on the threads, or why they didn't note this issue on the product page.
I also told them that I did not actually need a followup if they did not wish to: my purpose was to inform them, and it seems they already knew. It's been 5 days since my reply, so I assume I will not be getting a reply, which is also fine: other than to satisfy my curiosity or my desire to inform others, there's nothing that they *need* to reply about. So I consider this issue closed.
I have to say, I'm still confused. I just don't understand why these are being sold when they don't fit. But my confusion isn't really anyone else's problem, including Piranha. And now that I've taken matters into my own hands, it's *really* not Piranha's problem anymore. However, if anyone else has any further information on this -- especially future confirmation that the valve design has been changed -- please let us know.
Until then, before you buy these valves make sure you are prepared for the fact that they very well may not fit.
