I just want to share a great experience buying an o-ring kit from Captain O-Ring. I googled this a bit a week or so ago and found their web site which sold them in .22 caliber only. I asked about .25 caliber and bingo, they added them (and o-rings for .177) and proactively emailed me back when they were available on their web site. Jon was super-helpful, more than willing to accommodate my needs and FAST!