It depends on what you want to do and how fast you want to change magazines. The fastest is the Gen 2 or Gen 4 coupled with the Kingpin. This combination gives you the closest experience to a standard magazine release with all the benefits of firearm manipulation and malfunction clearing. Gen 1 is the easiest method to get you compliant and also the most economical. Gen 3 has the option for auto release but also incorporates a roller wheel on the arm to aid in closing the receiver. Gen 3 and Gen 1 will not work with the Dual Function Pin or Kingpin.
AR Maglock and any of the accompanying pin solutions was designed for mil-spec receivers. In most cases everything should work seemlessly, however certain modifications may hinder function such as cerakoting, wedges or set screws that tighten up tolerances and some other modifications to your receiver. Also other receivers made from billet that have added features such as ambidextrous bolt release or non mil-spec milling around mag release hole and rear takedown pin may prevent the system from working properly or hinder installation. Please make note of the receiver that you have before purchasing.
Gen 2 and Gen 4 as well as Kingpin work with rifles that have been broken in. Break in time from rifle to rifle varies but the more you shoot the rifle and the more the BCG settles into the upper receiver, the gap where AR Maglock fits when the receiver is open will increase the more you shoot the rifle. Certain rifles with enhanced BCG’s or buffer tubes may never open enough for this so again be aware that these units where designed to work with mil-spec receiver sets.
Again check that your receiver is a standard mil-spec unit. If you can verify this try using a standard magazine release spring. This will push the maglock farther out to clear the receivers being closed. As a last resort you can LIGHTLY sand the tongue of the AR Maglock back to aid the receivers closing. Proceed carefully and slowly and ALWAYS check that you have not sanded more than enough that the magazine will release with the receivers closed.
Again pay attention to the receiver set you’re using. Aero Precision includes a set screw that pushes the upper receiver upwards to keep tolerances tight. If your rifle has also been cerakoted or painted you may have to sand the rear takedown pin hole for the Kingpin to function properly. Also polymer/hybrid receivers have been known to cause issues with Kingpin function.
The Kingpin spring was designed with the end coils slightly tighter so that when the Kingpin is removed it will retain the spring so you don’t lose it. In most cases the spring will reset the Kingpin without issue. If your Kingpin seems to get “stuck” on reset, remove the spring and ever so slightly open one of the end coils. The side that you do not open inserts onto the Kingpin first so it will still retain the spring when removed. Test function and repeat until the Kingpin resets properly. Again proceed slowly and in small increments.
Please refer to the installation videos on the Gen 3 at the AR Maglock youtube page. The Gen 3 Kit comes with a small spring, a large spring and a spacer. If you want a standard push release use only the large spring. If you want auto release use the small spring and the spacer. In some cases the spacer may need to be sanded lightly to completely release the magazine. Again proceed slowly and in small increments
Since there really is no mil-spec standard for these platforms we have done our best to compile a database of which receivers Gen 4 will work with and have provided two different length stems depending on the receiver set you use. There will be a DPMS pattern that uses the longer stem and an Aero Precision M5 that uses the shorter stem. As mentioned we are trying to compile a database but if you know which receiver yours is patterned after you can make your choice from there. Gen 4 was designed to have some adjustability to aid in installation. During check out please specify long stem or short stem to accommodate your particular receiver.
We have design AR Maglock and the pin solutions to work in conjunction with each other. We CANNOT guarantee function nor compliance if mixed with another fixed magazine or rear takedown pin.