20 inch host with RDIAS

[Machineguntony]

I'm a big fan of the RDIAS. It is practically the only way for a civilian to own a 'new' machine gun, sort of.

My form 4 for the RDIAS was approved after only 4 months. I picked it up yesterday and installed it in my host.

At first I was going to go with a high end host, like a LaRue or Noveske, but then I decided on a cheaper host and picked this host for the express purpose of seriously abusing it with lots of mag dumps. Ah, the fun of an RDIAS.

The host I chose was a Colt AR15M4, 20 inch carbine (I love 20 inch full size rifles), which I ordered from Colt. It came from the factory with semi auto parts and needed a swap. Strangely, even though the Colt had all semi auto parts, and there was a sear block, it came with a full auto bolt.

I had a smith switch out the semi auto parts with auto parts and an auto hammer. Surprisingly, the RDIAS didn't need a shim. After the smith milled away the block, the RDIAS just dropped in.

I was a little worried about the timing of the hammer. The smith said that in his opinion, the RDIAS had a 95% chance of running.

I just came back from the range, and the gun ran beautifully, and without any hiccups, in full auto.

My only concern is that the RDIAS doesn't fit snug into the sear well. There is a slight and minimal amount of movement. I am concerned that this slight movement will gradually deform the sear. Is the RDIAS supposed to fit snug?

Here are some pics of my gun.



The switch moved to Auto. I haven't done the engraving yet, as I didn't expect the form 4 to be approved so quickly.



A side pic. I just love the 20 inch ARs.



A comparison of the 20 in full size rifle next to a 14 inch carbine. The 14 inch is an M16.



For those interested, here is a comparison of the internals of two full autos. The left is the AR with an RDIAS, the right is an M16 with the GI sear.

Here is a question for which the internet does hot have an answer...

When George Dodson (who allegedly may have invented the RdIAS) invented the RDIAS, why did he have to reinvent the wheel by creating the RDIAS, when he could have just copied the GI sear? I could understand the utility of the RDIAS design if the RDIAS could use AR parts, but the RDIAS still requires M16 auto parts. So why didn't any maker of AR sears just copy the GI sears and register the GI sear, thereby allowing the GI sears to be moved from host to host? You only hear of registered DIAS; I've never heard of a registered GI sear.

[Willie Lowman]

Because the GI sear requires an extra hole to be drilled in the receiver. The ATF considers drilling that hole manufacturing a new machinegun. So in the ATF's convoluted logic that idea is a no-go.