Threaded Holes on AR-15 Quad rails?

[harbl_the_cat]

What are the threaded holes on front and rear of the top rail of this type of handguard normally for?

 

[gunnyee12]

Typically they are used for QD swivels, but should not be threaded. Most are actually built into the side rails. Seeing as your looking in DX.com who knows what gimmick they're for.

 

[Farmboy]

Threaded holes are usually for screwing two piece rails together, or adding additional rails on tube style forends. Never, ever seen them on the top of a rail

Screw holes on the top of a airsoft rail is any ones guess.

 

[harbl_the_cat]

Funny, because this set Brownells is selling has the same holes:

 

[Runningfool]

Funny, because this set Brownells is selling has the same holes:

Isn't that just a pic of the handguard lying on its side (with QD holes)?

 

[harbl_the_cat]

Looks like QD holes is the consensus... I'll have to go home and try - I thought they were threaded, maybe I wasn't looking close enough.

 

[Pure Energy]

My Troy MRF-C has them spaced equally on all sides, I also wondered what they were for. Yes they are all threaded.

 

[mildcustom2]

Here is the best pic I could get of my Seekins/Spikes BAR quad rail Quick Disconnect Holes. As you can see there are small pockets machined for the balls on a quick disconnect mount to fit into.

 

[hbean]

"High Speed Low Drag" holes

Not a Mil spec requirement, on some rails are OD sockets, on some there are just there for ventilation.

 

[Pure Energy]

Like OP said though, what's the deal with threaded ones? To bolt accessories on?

 

[F22_RaptoR]

My Troy MRF-C has them spaced equally on all sides, I also wondered what they were for. Yes they are all threaded.

Threaded sling swivel or bipod studs.

 

[Pure Energy]

Threaded sling swivel or bipod studs.

That is what I figured. Why put them on the top though? In case someone installs it upside down? This is an older Troy, but their site still has the threaded top.