As it says:  Is there a standard for QD sling sockets?

Standard dimensions, etc...

I'm asking because I have a cheap railed HG on a carbine I am selling that

has a socket for a QD sling swivel at the end of the lower rail that won't retain the swivel

I have for it.

The diameter is correct but apparently the lip for the ball detents is not close enough to the

outer surface to allow the balls to lock out into place.

Has anyone else found dimensional variations between manufacturers?

I asked this same question a while back. No one knew if any standard dimensions had been created  for qd sling swivels.

There must be a standard that all manufacturers are using because the majority of them are compatible except some of the cheap brands.

Here's a list of what I'm using that are all compatible:

Blue Force Gear
Colt (Damage Industries QD swivel & Rogers stock)
Daniel Defense
Gear Sector
Knight's Armament Co.
LaRue Tactical
Magpul
Viking Tactics
Vltor

I guess I might have better luck in the BIY or AR Discussions forum, something the Industry Partners

might actually read.

You might try the Magpul Industry forum, those guys usually are helpful with giving more info.

I would guess that the socket OP has is a standard size, but that the attachment screw or bolt protrudes too high up into the socket for the swivel balls to make contact with the inside retaining lip.  Try a flatter mounting screw or bolt and it might work.

Nope wrong guess.

The socket is machined into a rail as the post states.  The hole goes all the way through and there is nothing impeding the swivel shoulder

from mating all the way up against the outer surface of the top of the rail.

There is no retaining lip per-se machined into the interior of the rail, just the inner surface of the original HG extrusion.

That is why I am asking what the dimensions of that lip should be.

Your original post made explicit reference to a lip.  Quoting you:

"The diameter is correct but apparently the lip for the ball detents is not close enough to the

outer surface to allow the balls to lock out into place."

It is for this reason I suggested that the lip was machined correctly but that the male end was not allowed to go deep enough to catch the lip.

Now you're saying there is no lip at all?  Which is it?  

I also could not find in the original post that the socket was "machined into the rail" as you claim it states.  Where was that?  Many sockets are attached separately.  

Not trying to be difficult, but also not accustomed to being slammed as a bad reader for not seeing what is not there and for trying to help.  Sorry for intruding in the thread.  

If there is no lip then there will never be any way to capture the detent balls on the male sling end.  

I got a B5 QD sling mount, I don't know which brand QD fits the sling mount fits the best.

Hell...I have a couple made in China that were very cheap but lock in perfectly to my mounts.  Go figure.

What brand aren't made in the USA? We need a list of QD that are made in the USA and a list of the ones made outside of the good old usa.

QD swivels are not all created equal

Impact Weapons Components

These are the only ones I'll use now.  [made in the USA]

I believe OP's problem is with the socket in the rail and not with the swivel.  But I agree that IWC's swivels are very good.  They will be of no help to him if his socket has no internal lip at all.