I highly doubt they had it labeled correctly (or doubt the sanity of the person that had the cylinder cut for it) as the back pressure causes the cases to set back and bind the cylinder, or worse. I know they were/are chambering them in some of the lower pressure bottle neck rounds like 30-30 and I heard possibly .375 JDJ, but nothing bottle neck with higher pressure than a contender.
http://www.magnumresearch.com/bfr_precision.aspThe website mentions some of the non-standard calibers their Precision Center will cut, but none of the bottle necks are listed???
