Posted: 4/23/2014 12:57:51 PM EDT
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Guys, I have a KMR rail here and I just ran into an issue. I'm trying to add a qd sling attachment, specifically the IWC part. That part will index into the slots fine, but qd sling swivels will not fit into the circular part of the slot (at least some of them) which is required in order for them to lock into the mount. I find that the qd swivels measure 0.375". They actually will fit into some of the slots, but not others. It turns out that they won't fit into any of the slots in the area I need to attach the sling to.
According to the keymod drawing, I believe the diameter of the circular part of the slot should be 0.380" and that would work ok with the qd swivels. So, I have a few questions: Is the design of the IWC qd mount an incorrect use of the keymod slots? Are some of the slots on the rail out of spec? The best I can measure with my calipers shows that the ones I want to use are 0.370" diameter, so it's definitely an interference fit with the qd swivels. Should I just lightly sand inside the slot that seems to be undersized where I want to attach the sling? That doesn't seem like a good solution since it would remove the protective coating most likely, but I'm no expert on this alloy. Sorry to post this here but I need this rifle to come with me groundhog hunting on Friday or Saturday and I'd prefer to carry it on a sling. I will also email BCM...just looking for some fast input so I can figure out what to do. |
| Don't take this the wrong way, but are you sure you're installing it correctly? The reason I ask is that a while back I read somewhere (can't remember if it was this forum or another one) where someone was having a similar problem and as it turned out he was either trying to install the sling point backward or didn't have it properly seated into position or something like that. |
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Quoted:
Don't take this the wrong way, but are you sure you're installing it correctly? The reason I ask is that a while back I read somewhere (can't remember if it was this forum or another one) where someone was having a similar problem and as it turned out he was either trying to install the sling point backward or didn't have it properly seated into position or something like that. Yes, unless there's more than one way to put a round peg in a round hole 
I installed it just like this (from IWC website): 
The round hole in the mount lines up with the circular part of a keymod slot so that the qd swivel can be inserted enough to lock into the mount. That is, if the keymod slot is made to the spec. ETA: I guess another possibility is that all of my qd swivels are out of spec. But I don't know what the spec is on those, and I do see that the keymod slots are not to the spec. ETA2: The problem can be observed without even installing the qd mount. Just try to put the round peg (the qd swivel base) into the round hole (circular part of the keymod slot) and it won't go. That seems to be necessary in order to use the qd mount. |
It actually is directional--turn it around and double check that the mounting pieces are turned the right way also. Been there, done that.
IIRC, here's a small tab that prevents it from moving back and forth, but but it has to be on the correct side to seat properly. If it's flipped, you can tell by looking through it that the hold in the QD and the hole of the KeyMod slot don't line up completely. |
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Quoted:
It actually is directional--turn it around and double check that the mounting pieces are turned the right way also. Been there, done that.
IIRC, here's a small tab that prevents it from moving back and forth, but but it has to be on the correct side to seat properly. If it's flipped, you can tell by looking through it that the hold in the QD and the hole of the KeyMod slot don't line up completely. I haven't been there and done that...I have the qd mount installed correctly as shown above. The holes are lined up but the hole in the rail is too small for the qd swivel to insert. Problem seems to be with the rail and not with the IWC qd mount. Anyway, I received an email from BCM and the rail is going back to them. |
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I ran into the same issue when installing mine. There is a little play in the setup in regard to where you place the qd mount before tightening down the screws. I assumed you would want the mount placed so the front nubby fits against the wall of the slot it sits in. If you then tighten it down the qd swivel won't fit in. I got a bit puzzled by it also until I just centered the mount so it fit proper and tightened it down. It holds real good and I it hasn't loosened since I installed it. Of course yours could be different but I figured I should comment since i had the same concern at first. Good luck!
Edit - never mind! I didn't see where you mentioned that the socket wouldn't fit into some of the slots even without the mount. That does sound like a problem! Bcm will handle you proper I'm sure. |