A Drop In Auto Sear (DIAS) or RDIAS is a device that adds an auto sear to an otherwise semi-automatic AR-15 so that when used with M-16 fire control parts including an M-16 carrier produces full auto fire. There are two types of AR15 Drop-In Auto-Sears (DIAS) available:
(1) the so-called ”legal pre-81” auto sears
(2) the registered auto sear
An auto sear made before 1986 and registered (tax paid) with the BATF is a machine gun capable of transfer to a qualified average joe. Post 1986 DIAS's are typically considered 'post-samples' and not available for individuals.
Who Made Drop In Auto Sears?
There are an estimated few thousand registered Drop-In AutoSears, made by a variety of companies such as Broadhead Armory of Wyandotte Michigan, F.B. Whitman and Son of Winsted Connecticut, Qualified, SWD, RPB, Desert Ordnance, Small Arms Research, SAC and others. Another type is the "X-Ring" RDIAS (AR-15) "Tool Steel" Auto Sear.
Above: Example Registered DIAS
What are DIAS made of?
The more desirable DIAS's were made of steel while other variants were made totally of aluminum. Lastly, some were made of aluminum with steel trips.
How Many DIAS were legally manufactured as transferables?
- DLO Mfg registered approximately 10 M16 DIAS. They all were aluminum bodies with steel paddle. None were all steel.
- C Ray Systems also made a M16 DIAS. Users report fitting trouble with the upper receiver lug with this DIAS.
- The Hard Times Armory DIAS is steel. It is a marked " HT ARMORY Smyrna GA".
- The Broadhead Armory DIAS is listed as a BA15 (M16) auto sear.
- The Neil Smith DIAS are made of steel. The DIAS should be engraved, "Neil E Smith, Mentor, OH" followed by the serial number.
- The DIAS manufactured by John Norrell is made with a steel body.
- The SWD registered drop in auto sear have an all steel body and flapper. "SWD" is electro-penciled on the side.
- The F.B Whitman & Son DIAS is made of aluminum with a steel flapper.
- The Chasen Corp DIAS is all steel.
- The JCB DIAS is made of steel.
- The Smith Enterprise DIAS is made of steel. The serial number will start with "00" stamped with marking "Smith Mesa AZ"
- The Desert Ordnance DIAS is made of steel.
What is a Lightning Link ?
Above: Lightning Link installed in AR15 receiver.
There are an estimated 500 registered SWD Auto-Connectors in private hands.
SWD Lightning Link (SWD Auto Disconnector or Auto Connector) is one of those unique solutions where someone happened to look at the operation of the AR-15 and how the various parts of the operating systems work together to find an easy way to convert a semi-automatic firearm into a fully automatic weapon.
Above: SWD Auto Connector with KNS Link protector
For more description of the history and function of the Lightning Link : http://www.quarterbo...htninglink.html