I have a Kelby on my 40x rimfire- not had any issues at all. At the time I was looking for something Jewels were experiencing problems mostly at the most in-opportune times, didn't need/want that. As I was switching from my Canjar due to needing unobtanum repair/ parts. At that time B&A and FF were likely only on the drawing boards- if that even. The Kelby was the new kid on the block back then.