Transparent magazines have been one of the most difficult things to accomplish in polymer. Most examples we see have flaws, usually fragility in the magazine body, and cannot be recommend as readily as solid color counterparts.
The GenM3 PMAG has been the international standard for STANAG Magazines and Magpul does not want to compromise this standard for a feature that is, in part, just a creature comfort. Magazines need to feed rounds into the weapon, being able to count the remaining rounds by sight is a luxury that does not improve efficacy if it compromises the weapon’s reliability.
The TMAG, offered in ODT (Olive Drab, Transparent) apparently meets Magpul’s GenM3 standards, but now with the estimate windows replaced by total transparency (in a manner of speaking). The windows and marked follower in the PMAGs were decent, but no substitute for total visibility.
In addition to TMAGs, the AMAG introduces the step into the aluminum magazine space for pistols
Starting with the institutionally popular P320/M17/M18, the AMAGs are going after the pistol markets that do not do so well with polymer designs. Rifle magazines tend to play well in polymer, but pistols limited space and designs originally metallic dimensions in mind make polymer unusable (at least at present).
Just as it is nearly impossible to make an AR-15 or AR-10 lower out of polymer because it is based upon the strengths and dimensions available out of aluminum, a space designed with aluminum or steel dimension requirements in mind can be very difficult to adapt to polymers.
If it isn’t broke…
AMAG. I’m hoping the M&P 2.0 and P365 will be hot on the heels of the P320’s