Interesting that you have found that high velocity is needed, I presume, to cock that big, heavy hammer. Mine works better now that I have polished the trigger-group parts and reduced the hammer spring strength.
The V22 AR-15 22LR Dedicated Upper manual states:
"Ammunition: The V22 Conversion unit is designed to fire 22LR high velocity ammunition reliably. Use of other than high velocity ammunition might lead to functioning problems and is therefore discouraged."
An e-mail from TG at the importer's site told me:
"High velocity ammunition will frequently not work and is not recommended for use in the V-22 upper. The non-firing situation is a problem that we have not experienced in any of our test units. We have several uppers undergoing long term testing, some of which have more than 3k rounds so far, and the testers have not reported any such incidents."
After I sent him the above quote, he/she hasn't e-mailed me again.
I also find it interesting that some of the uppers had already shot more than 3k rounds. If you check some of the .22 boards you will find that most of us shoot that many rounds in a week or so. Interesting indeed.
Wade