LL selective fire kit

03/26/04

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Selective Fire Kit for Lightning Link Using AR-15 parts
presented with a little help from Mouseomatic of AR15.com
 
Drawing showing  modified Disconnector
of the selective fire kit described on this page.
 

The best way to begin this page is by referring you to my Lightning Link Page which provides an overview of the Lightning Link.  The Lightning Link works in a standard AR-15 as described on the Lightning Link Page and one of the historical disadvantages of the Lightning Link had been that the Lightning Link converted an AR-15 to full auto only (non-selective fire).  Scott Bell and John Norrell developed a solution to this problem a few hours back in 1990 by creating a selective fire parts kit using a M16A2 style selector and trigger along with two disconnects as described at the bottom of my Lightning Link Page

One disadvantage with the selective fire parts kit as developed by John Norrell and Scott Bell, which is sold by Scott Bell to this day, is that the parts used to make the Lightning Link selective fire are M-16 parts and if the Lightning Link was removed from the AR-15, the owner of the AR-15 could find themselves in an legally compromising position for having M-16 parts in an AR-15.

Legal  note: as long as a LL is installed in an AR-15, then the AR-15 is part of the machine gun or in this case the AR-15 is a part which is connected to the lightning link.  As soon as the LL is removed, the AR-15 is no longer part of the machinegun and all NFA rules would apply.  Any M-16 parts that remain in the AR-15 would need to be removed to prevent a potential violation to the National Firearms Act.

Following is a diagram that shows how a Normal AR-15 looks and then a normal AR-15 with a Lightning Link..

Normal AR-15

Normal AR-15 with a Lightning Link

In this page, I am going to present a new design for a selective fire parts kit that uses AR-15 parts.  The use of AR-15 parts should be obvious as with these modified AR-15 parts, no M-16 parts are ever used in an AR-15 so the Lightning Link can be removed and the rest of the parts can remain in the lower until the next time the registered owner wished to use their Lightning Link!

Well, let's try to discuss this new kit!  The selective fire parts kit that I am trying to describe in this webpage consists of two modified parts.  The first is the disconnector and the second is the selector.  When you look at the photo above and to the right that the selector is round inside the receiver pocket and it holds the link up slightly on the disconnector as illustrated.   This selective fire parts kit uses this fact to allow the lightning Link to become selective fire with AR-15 parts.

This is accomplished by milling the top of the selector that is exposed in the receiver pocket flush to the top of the receiver pocket ledge when the selector is set in the semiautomatic position.  A scribe is then used to mark where the top of the lightning link rests on the disconnector.   The disconnector is then removed and an angled notch is cut into the disconnector 0.020-inch  wider than the link and .035 deep.  With these changes, a Lightning Link will not catch the disconnector when the selector is placed in the "SEMI" position.

To allow the lightning link to work in an third "AUTO" position, the selector will then need to have a groove milled into it with a small detent recess for the third position.  As long as the selector retains it's original diameter this third "AUTO" position will raise the Lightning Link above the notch prepared above allowing the Lightning Link to release the disconnector producing full auto operation when the selector is placed in this position and the weapon is fired with the trigger depressed.  The selector will also need to be milled on the bottom edge such as to allow the disconnector to operate, as opposed to being blocked like in the "safe" position.

Another option to create a selector that would provide the "THREE" positions necessary for this kit would be to use a M-16 selector as a starting unit.  In this case, the selector would need to be milled flat as described above for the "SEMI" position and the third position could be basically left alone for the "AUTO" position.  The extra groves as used with the M-16 Auto Sear could be filled with JB Weld or other means such that the selector would no longer function in an M-16.  Using the M-16 selector has some advantages as it would be a simpler modification but it also has the disadvantage as once again we have an M-16 part that we are using in an AR-15.

Quarterbore's Note:  I am planning to write the ATF for clarification if using the an AR-15 selector that is milled for three positions OR using a modified M-16 selector would cause potential non-compliance with National Firearms Act regulations.  Given that this system is actually a system designed to allow for selective fire, which would promote safety, and it tries to solve the potential liability issues associated with the traditional options, I hope that the ATF will look favorably on one or both of these options.

Following are two photos that demonstrate how this selective fire parts kit would look in an AR-15 with a registered Lightning Link.

Modified Parts in Semi auto position

Modified Parts in Full Auto position

Given that this selective fire parts kit uses AR-15 parts as opposed to the M16A2 components of Scott Bell and John Norrell's design this is an interesting alternative! 

 

 

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This site was last updated 04/15/03