Various firearms featured in game have the option to have variable length magazines that will show no visible change to the magazine's length. I would like to see that change. Examples include: 9 mm pistol 30 round magazines for Rook-40 and P07 pistols, PDW2000 to show 9 mm 16 round magizines, SDAR 5.56 mm magzines to show whichever magazine is not currently showed when equipped (I can't recall if 30 round or the UW 20 roud is visible when loaded), and I think the last one is the MXSW with the option to load the 30 round 6.5 mm magazines.
From a game physics point of view perhaps more rounds in the magazine could have less stable aim when not prone. You viewers may argue that point with me as I am unsure myself on that matter. Just trying to keep it "real."
Thank you for your interest.