The Polish magazine Bron Amunicia TAC has recently made light of Fabryka Broni releasing both a 7.62x39mm version of the MSBS at the International Defense Industry Exhibition MSPO in Poland, and a STANAG compatible 5.56x45mm magazine (separate from the exhibition). Having a 7.62x39mm model or conversion has always been of interest since the early 2000s among a number of firearms manufacturers. It originates from a civilian market that wants to make use of the 7.62x39mm round in firearms other than the AK, in addition to a number of military groups that see potential in the round being used for a battlefield pick up, or allowing the ability of forces to convert their existing battle rifles to fire the enemies ammunition. Of course, this scenario is really only forceable with SF types that encounter enemy munitions, and not your line companies that would probably only be around significant enemy ammunition during a siege or similar situation.
However, the more important consideration with 7.62x39mm is that the current Polish military rifle, the Beryl, is an AK design chambered in 7.62x39mm. Thus, if the MSBS is going to be competitive in the future, if the Polish military doesn’t want to change over to the 5.56x45mm round (which the MSBS is currently chambered in), then this would open up the competition to the 7.62x39mm.
The polymer STANAG magazine appears to come in two versions, one 30 round version with cartridge windows (at 20 and 30 round marks) and another 10 round version without cartridge windows. At this point in time the only images we have at hand seem to be graphic design images and not tangible production items. Although the article states that the magazines were produced because Fabryka Broni wanted a domestic supply of magazines, I would like to venture otherwise. The 30 round magazine can incorporate a cartridge limiter, similar to how many CA magazines are being made. In addition to the 10 round magazine, I assume that these magazines are actually being made for the U.S. market. Fabryka Broni could just as easily produce aluminum magazines for their own military and LE markets, so why even bother with a polymer 10 round magazine and limiter for the 30 round, that would be perfect for civilian import? Another explanation is for the parade purpose of the magazine. Recent pictures have showed some Polish military units parading with 10 round magazines inserted, probably loaded with blanks or not loaded at all.
Thank you to Piotr P. and Hecheyra H. for contributing to this post!