The CL-MAG™ offers for the first time a reliable and efficient 150 rd magazine for the .223/5.56mm rifle. Designed to fit NATO standard (STANAG-4179) rifles, the CL-MAG™ quickly converts a rifleman with a standard M4 into automatic support personnel. The 150 rd magazines have been routinely emptied through the standard AR-15 setup without weapon failure. (Ambient temperature starts). The flexibility of such force multiplication makes the CL-MAG™ the most dominant accessory for the AR/M4/M16 family of weapons.
I must say I don’t get it. If the magazine breaks you are stuffed unless you are carrying other magazines. For example you may have to carry a 150 round CL-MAG, as well as 3×30 round magazines. If the CL mag jams after 50 rounds you are now carrying 100 rounds less than you were a minute ago.
On the other hand the Singaporean 5.56 LMG, the STK Ultimax 100, the same people who make the CPW, takes STANAG magazines and currently uses a modified 100 round C-Mag. This would give it 50% more capacity and increase rate of fire. The added weight may even be beneficial (when being fired, not carried).
Photo from Wikipedia.
The Ultimax 100 is being marketed to the Marines. It is has very low recoil, takes standard M16 magazines and can be operated by one person.
The weapon in action: