The JAK12 will appear as the Steakout12G/AA12 and more or less clones the stats.
The only gimmick for the single gun is the separate animations for the magazine and drum, as well as a few attachments that let you bump up the concealment. Those short/concealable attachment wont beat the vanilla Saiga/Izhma but it's something i guess.
The akimbo JAK12 is a meme weapon I inserted last minute into development because why not. Will appear as the Akimbo VD12s/Sko12s and mostly clones that gun's stats, except for aligning the concealment/damage/ammo count sorta in line with the vanilla AA12.
Known Issues
If you previously had the gun from years ago when it used the Germantacos (X) Pack format, manually redownload the gun from the mod page. The (X) Pack file format will likely conflict with the new version.