I tried a B1 for a bit this summer(from Amazon) but it started acting badly. My BIL was loading it,it got away from him,slammed shut so the barrel was bent.The notch in the spring guide in the piston was off center,so it was never holding the sear by much. I tried shimming and regrinding, etc.It went down the road! lol I have a B3-2 in .22 that's great.
Love it. I'd like to try it with a B2.