The BM operates at higher pressures than the SOCOM and requires a bolt made of special steel. The bolts are physically similar otherwise between the two, with the ejector moved farther from bolt center and the extractors modified for the larger radius of the case head. It is ill advised to use a .45 ACP/.458 SOCOM bolt with the BM due to possible lug shear. The BM also has a much slower rate of twist typically, since it isn't designed for subsonic use with heavy bullets. The BM case staggers slightly in an AR magazine, causing bulging issues. One of the big pros to the SOCOM is the extra-fat, bottleneck case which single-stacks well in an AR magazine and center-feeds from unmodified feed lips. The bottleneck aids feeding and I've never had a single hiccup with mine. The pressure limit of the SOCOM at 35K psi is an engineering assumption extrapolated from case head diameter and bolt thrust limits established for the 5.56 NATO, and is much less than what I understand the 450 BM to be, hence the requirement for special bolt steel.
Lots of people like the BM, but caveat emptor regarding the collection of parts you have. Tony Rumore also sells 450 BM bolts and parts, you could check with his site Tromix dot com and peruse the list, but you will not be guaranteed proper headspace.