Jim, I'm going to have to disagree with you on RLL's and RDIASs being "junk". Having owned all three types of FA AR15/M16's (receiver, sear, and link) I can honestly say my preference is for the RDIAS. Even an aluminum one can outlast a receiver gun. Although its rare, the trips on the RDIAS can break and wear out, but they are a replaceable part, and subject to no more or less stress than the sear in a receiver gun. Similarly, they can be replaced to alter the timing if necessary. A steel body RDIAS can definitely outlast a standard receiver gun. Moreover, if you beat up the lower in whichthe RDIAS is installed youcan simply replace the lower receiver with any currently made AR15 receiver. Once properly installed and timed, reliability with a sear is excellent.
While the RLL is a little less reliable due to the wear and eventual bending of the trip on the link, the trip levers on the link are replaceable parts also, and even if installed in the gun can be changed in a matter of seconds. The body, or serialized piece of the RLL, have been known to eventually break, but KNS is now making a steel reinforcement plate for the RLL body which will prevent breakage.
It is legal to own an unregistered (not serial numbered) DIAS or lightning link made before 1986, but it is illegal to have it in a rifle or to also have a rifle into which it will fit.
Not exactly true. Its illegal to possess an unregistered sear made after 1981. BATFE promulgated a rule in 1981 that sears made after that date had to be registered, thus putting into question the legality of mere possession of unregistered sears made
prior to the 1981 ruling. The one federal circuit court that has addressed that specific issue noted that the BATFE didn't have the authority under the NFA to issue the 1981 ruling "grandfathering" unregistered sears made prior. The only possible effect BATFE could have had with the 1981 ruling, according to the court, was to provide an amnesty and free registration period for sears made prior to the 1981 ruling which necessarily ended at the May 1986 registration cutoff. This decision clearly divided the world of sears into two types - registered and unregistered, and all but invalidated the 1981 ruling as a potential defense to posession of an unregistered sear made prior to 1981.
Even if you go by BATFE's old rule and completely disregard the above case, its important to understand that the burden of proof was still on the possessor of the unregistered sear to show it was made prior to 1981. Since there's no serial number on an unregistered DIAS and no way to definitively link it to a date of manufacture, one possessing an unregistered sear he claims was made prior to 1981 would still be in serious jeopardy of a criminal conviction.