DDM4/SLiM rail anti-rotation problem?

[mtdawg169]

It's a little hard to explain without showing you. The bolt up plate is not sandwiched between the barrel nut and the receiver. The barrel nut inserts through the plate.

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[bowman57_2]

I've wanted one of the DDM4 rails for a long time but other stuff always got in the way and now I don't really know if I still want one. My work rifle has a RIS II on it and I've beat the living hell out it and it has always just came back asking for more, and theres been plenty of guys before me that have done the same to that same gun. I know the RIS has 2 more mounting screws, but I don't see how 3 small drops could knock this rail off center and my RIS is still going strong.

[justin_247]

Rail shifted again in AKOU's tests, despite having been reinstalled with Loctite.

https://youtu.be/vHEG0dtfwq4?t=3m21s

[awdxtc]

Pretty disappointing. My v5 has zero rail shift after 8000 rds, then again I don't use it as a club.

[justin_247]

Pretty disappointing. My v5 has zero rail shift after 8000 rds, then again I don't use it as a club.

Yup, no problems here, either (I use the Lite III, but it has the same attachment method).

I just think it's important to highlight this problem to encourage DD to develop a more durable attachment system. The rail is amazing, but the attachment system brings it down quite a few levels.

[awdxtc]

Over on the ak files Rob stated that he will be meeting up with them a SHOT

[jackblack73]

Pretty disappointing. My v5 has zero rail shift after 8000 rds, then again I don't use it as a club.

He didn't use it as a club either. Just dropped it multiple times. Nothing too aggressive or unlikely to happen.

[Torquetard]

The reason DD advises against using loctite in the screws is because they will strip if you aren't careful. Hand tight is fine, but any harder than that and your hex bit will all of a sudden be spinning when the screw isn't..

[ODgreenpizza]

If I had a rotation issue with one of these rails the following would be my "maximum effort" re-install procedure:

1. Chase threads in rail w/ screws to reduce chance of imperfect thread engagement
2. Thoroughly degrease screw threads, hole threads, exterior of bbl nut, any surface of rail and bolt up plate that contacts bbl nut
3. Apply thread locker to screw threads
4. Install rail with screws finger tight then torque to mfr req spec of 32 in/lbs in diagonally opposed sequence

It seems uniform clamping force between rail, plate, and bbl nut is crucial for preventing rotation in this design. Longer rails and rails with lots of stuff mounted may be more prone to rotation.

[RJflyer]

I'm not sure why DD would say to avoid using loctite on the screws. I just checked my DDM4A1's rail screws and they all had factory-applied thread locker on them. None were loose, but then again I haven't dropped my gun on concrete.