The holy grail of the AR platform may just be the .30-caliber round. Frankly, the 5.56mm cartridge has its limitations. It’s great for many things, but for others—not so much. Most operators have no issues, especially with use of the correct bullet. But for many, especially in the military world, it is just too small. You can move up to the 7.62x51mm, but that cartridge has suffered its own set of issues in this platform. It is also expensive, and for many police departments, it costs too much. The real solution is a 7.62x39mm cartridge that will actually work in an AR-platform rifle.
Although the police world has not jumped on the .30-caliber bandwagon as strongly as many in the military, it is growing in popularity. Rural departments are moving to the 7.62x51mm for patrol, mostly for its long range and solid knockdown capabilities. That does not really help the entry team or urban agencies, though, and that is where much of the “short 30” focus has been placed. Several attempts have been made to make the 7.62x39mm work in the standard AR with mixed results. You can generally get the round to work—you just have to use a proprietary magazine.
Unfortunately, the choices are few, and the ones that really work are fewer. Given their availability, they are often two or three times the cost. Even relatively successful calibers like 6.8 SPC experience some of the same magazine issues. What is really needed is something that will work with standard magazines, even if they are downloaded a bit. Wilson Combat may have come up with a workable solution.