AR15.Com Archives
 Investigating stripped lowers... What is RDIAS/RLL compatible?
mattmcg  [Member]
10/16/2006 2:33:17 AM
I've been looking at the different lower receivers out there and keep seeing a term that I don't understand. On certain stripped lower receivers it will state that it is RDIAS/RLL compatible while others don't.

So my questions are:
1. What is it and what does it do?
2. Is a Stag lower RDIAS/RLL compatible?
3. What does the difference look like on the forged receiver (if any)?
Arc_Angel  [Member]
10/16/2006 7:49:04 AM
RDIAS = Registered Drop-in Auto Sear
RLL = Registered Lightening Link

Both are used to convert a normal AR-15 lower receiver to allow full-auto fire. These parts are controlled like machine guns, so don't go buying one of the $100 ones advertised in the back of the Guns and Ammo.

I think in order to install one, your lower can't be blocked (I've forgotten the exact term) that prevents installation. Some lowers have them and others don't. I don't know about Stag.
Phoebus  [Team Member]
10/16/2006 1:18:01 PM
If you don't know what an RDIAS or RLL is, then you don't need a compatible lower.

These enable full-auto fire, and will cost you 8-10 grand if you want one.
mattmcg  [Member]
10/16/2006 1:34:40 PM
Don't need one (obviously) but was just curious about what the acronyms meant.

Sounds like different stripped lower receivers will be forged differently though, which was the reasoning for my question......

Phoebus  [Team Member]
10/16/2006 1:36:03 PM
Nope, forged the same, just has to do with how the interior is machined.
sevensixtwo  [Member]
10/16/2006 2:35:05 PM
In addition to what Arc_Angel said...

The rear "shelf" (where the safety selector passes through) is what matters for the RDIAS. If the shelf is too high, a RDIAS will not fit in there (this is done intentionally so that the lower can not be used with a DIAS). You'll see the term "Low Shelf" and "High Shelf".

Phoebus - He needs one, he just doesn't know it.

I believe that STAGs are high shelf. The difference isn't in the forging, it's in the final machining. Here are the differences:



Notice the difference in the space between the shelf and the take down pin. The easiest way to tell is to look at the selector hole. A high shelf is the same height as the top of the hole, a low shelf is just above the middle line of the hole.
FMJ  [Team Member]
10/16/2006 2:50:23 PM
The low Shelf looks pretty thick on the right side?

looks like a sear wouldnt drop in Unless there was some Machineing on the right side
sevensixtwo  [Member]
10/16/2006 4:37:47 PM
Oh yeah, I left that part out...that's the other difference...it's the hold the DIAS in the correct location. The high shelf obviously doesn't need that extra machining step so they leave it out.