Having issues with certain keymod mounts.

[HansTheHobbit]

A few months ago, I had a keymod bipod adapter come loose on me. I wasn't even shooting the rifle at the time. I had just installed it, and was sort of playing around with it and it just came loose. I reinstalled it, torqued the crap out of the screws, and wrote it off as a fluke.

Well, a few days ago, I installed a light mount on a different rail. The first rail was an Vltor VIS, this time was with a BCM KMR Alpha. Pretty much the same thing happened. I installed it, checked to make sure everything was good, then leaned it up against the wall in my office. The next day I picked up the rifle and it flopped to the side. Somehow that thing had come loose all on its own overnight. I don't have dogs or kids, so there's no possible way that it got messed with. It didn't fall over, either. It was sitting just as I had left it the night before.

So I got to thinking, why would this happen when I have two QD sockets that have never come loose. One of them is on an SPR that weighs ten pounds loaded, so it's supporting quite a bit of weight, and I didn't even have to torque the screws all that much to get it to stay in place.

I got to looking at the differences in design between the QD sockets and the mounts that had come loose, and there were immediately some obvious differences between the two categories. Both QD sockets were designed the exact same way (one was vltor, the other BCM), where the indexing tab went to the next slot, thereby "pulling" the feet forward. This was opposed to the other two mounts, which had the indexing tabs placed to the rear of the screws, such that the tabs were "pushing" the feet forward into their little slots. The bipod adapter actually shares a common indexing tab for both screws, placed in the middle, such that it's pulling one foot forward, while pushing the other one. This design seems to be pretty common amongst all the various brands of mounts of all kinds.

I was wondering if anyone else has had any problems, and if so, have they noticed this same trend.


ETA: I forgot to mention, I do not think loctite is the answer. I'm not totally unwilling to try it, but I'm 99% certain it won't help anything. The problem doesn't seem to have anything to do with the screws backing out, especially since I don't see any way a screw could possibly back itself out while the gun was leaning against a wall all night.

My first try at a fix is going to be to fully torque the rear screw first, then the front one. I think tightening them incrementally at the same time is causing the indexing tab to not fully engage in the slot. So if anyone is having the same issue, then it might be worth it to try this. We'll see how it goes.

[SteveL]

I thought the standard method for securing keymod items was for the indexing tab to go into the next forward notch to keep the keymod mount from being able to move backwards once everything is tight. Having the tab at the rear doesn't make sense.

Care to share which specific items (manufacturer and model) you're having problems with?

[HansTheHobbit]

I thought the standard method for securing keymod items was for the indexing tab to go into the next forward notch to keep the keymod mount from being able to move backwards once everything is tight. Having the tab at the rear doesn't make sense.

Care to share which specific items (manufacturer and model) you're having problems with?

The bipod mount is from Odin Works, and the light mount is an Vltor Millennium mount. But I want to emphasize that both mounts are designed identically to most other keymod mounts I've seen in terms of their interface. For example, the Odin Works bipod mount is functionally identical to all the others on the market, with one indexing tab in the center of the two screws.

Now the Vltor mount is somewhat different because it has two indexing tabs, both to the rear of the screws. In other words, the indexing tabs interface with the rear portion of the same slot that the foot slides into. Most keymod mounts I've seen only have one indexing tab in the center, as with the bipod mount.

[GH41]

Put up some pictures of the bottom of the accessories. My bet is the nuts are reversed and you don't understand how KeyMod works. Stuff assembled and installed correctly doesn't fall off by itself. Even with the screws barely tightened they won't fall off. Pictures or it didn't happen.

[HansTheHobbit]

Put up some pictures of the bottom of the accessories. My bet is the nuts are reversed and you don't understand how KeyMod works. Stuff assembled and installed correctly doesn't fall off by itself. Even with the screws barely tightened they won't fall off. Pictures or it didn't happen.

Buddy, you're the one who doesn't understand how keymod works. What you're proposing isn't possible, for several reasons.

Just to clarify, though, nothing "fell off." It just came loose.

[AM-15]

I have a DD Keymod Harris bipod adapter on my PWS handguard.
From forward to back.
Screw and locating tab in first slot.
Locating tab in second slot.
Screw in third slot.
Has never moved or loosened and no Loktite involved.

Clarence

[SteveL]

Buddy, you're the one who doesn't understand how keymod works. What you're proposing isn't possible, for several reasons.

Just to clarify, though, nothing "fell off." It just came loose.

There have been instances on this forum of keymod mounts with the hardware reversed causing problems similar to yours. My guess is that you're putting your mounts on backwards.

[wildcard600]

I don't understand how its possible for a keymod acc. to come loose if properly installed unless the accessory itself isn't designed properly. Looking at my BCM KM stuff the only way it could conceivably happen is for it to be installed backwards.

Pics of the parts might help us to understand.

[P2000]

Some keymod accessories like MI rail covers do not prevent the nut from rotating, so during install it can turn backwards. Maybe that happened?

[GH41]

Buddy, you're the one who doesn't understand how keymod works. What you're proposing isn't possible, for several reasons.

Just to clarify, though, nothing "fell off." It just came loose.

What is the difference between falling off and coming loose? Your thread is a perfect example of why KeyMod is not idiot proof. Some people have problems following directions.

[556BlackRifle]

I have two keymod rails with picatinny rail sections in front at 3 - 6 - 9 O'clock. Bipods at 6, weapons lights at 9 unused at 3. Also a QD mount at the rear. The QD and Bipod points see the most stress. Never had any of these connection points loosen up.

I'm guessing that either the rail or accessories are out of spec / installed incorrectly.


https://www.youtube.com/watch?v=g2oIlcbzzZ0

[HansTheHobbit]

Like I said, there's no way the mounts could be backwards. If that were the case, then they would have destroyed my rails, especially as tight as I torqued the screws this time around. The Vltor Millennium mount especially is pretty much impossible to mount backwards.

As for the screws themselves being backwards, again, it's not possible. Both of the mounts in question limit the rotation of the feet. Even if I were a complete idiot, in order to get the screws backwards I would have to uninstall them from the mount and reinstall them backwards. And not only are the feet locked in facing front, but the screws can only be backed out far enough to install the mount, making it virtually impossible to rotate the feet into the wrong orientation.

Finally, why am I only have problems with these two mounts? Why in the hell would I install all my other keymod stuff correctly, some of which is not as obvious, and somehow have a total lapse of sanity every time I install the two in question???

[Airhasz]

I also had the 'keymod ah ha moment' where you see exactly how these mounts are correctly installed.

[Iraqgunz]

We had someone come in the shop last week with Odin Works stuff and issues. I have seen enough of their product to realize I want nothing to do with it.

On another note. Why don't you post some pics? We aren't asking for your help, you are asking for it.


Like I said, there's no way the mounts could be backwards. If that were the case, then they would have destroyed my rails, especially as tight as I torqued the screws this time around. The Vltor Millennium mount especially is pretty much impossible to mount backwards.

As for the screws themselves being backwards, again, it's not possible. Both of the mounts in question limit the rotation of the feet. Even if I were a complete idiot, in order to get the screws backwards I would have to uninstall them from the mount and reinstall them backwards. And not only are the feet locked in facing front, but the screws can only be backed out far enough to install the mount, making it virtually impossible to rotate the feet into the wrong orientation.

Finally, why am I only have problems with these two mounts? Why in the hell would I install all my other keymod stuff correctly, some of which is not as obvious, and somehow have a total lapse of sanity every time I install the two in question???

[HansTheHobbit]

We had someone come in the shop last week with Odin Works stuff and issues. I have seen enough of their product to realize I want nothing to do with it.

On another note. Why don't you post some pics? We aren't asking for your help, you are asking for it.

Posting pics isn't going to accomplish anything, and it would involve me removing the keymod stuff again, finding my camera, syncing it to my computer, screwing with photobucket, etc etc. If there was a point, I would be more than happy to, but there isn't. I've been using keymod for quite a while now, 99% successfully, so I'm 110% positive that everything is installed correctly. Besides, I told everyone what mounts I'm using, and there are much better pictures online than I'm capable of taking with my camera.

As for the Odin Works bipod mount, I don't think there's really anything wrong with it that isn't wrong with every other keymod mount that uses the same setup. The fit and quality in general is just as good as any of my other keymod stuff, so I don't want to give anyone the idea that I'm down on a specific brand.

Again, I've noticed these problems seem to revolve around a specific placement of the indexing tab, not any particular brand.

[nolt]

We had someone come in the shop last week with Odin Works stuff and issues. I have seen enough of their product to realize I want nothing to do with it.

On another note. Why don't you post some pics? We aren't asking for your help, you are asking for it.

I actually don't think he wants help.

I think he's here to proclaim/declare/allege that keymod stuff is falling off of his rifle in an unadulterated and unprovoked manner (while not being used,) and furthermore to connect, network, and discuss said phenomena with similarly-afflicted people.

I think it would be awesome for there to be a support group somewhere for all the people that get white knuckles and strained forehead veins when they throw themselves into fifty page threads attempting to proclaim a victor to this 'war' that's being waged inside their heads. I'm not accusing the OP of being one of 'those people' but I can feel the ground shaking already. ;)

[themonk]

Is it the odin works mount with the harris bipod adapter? If so, just as a data point - I had that mount and had two problems 1) where the bipod mounts it does not have a lot of connective metal which is also aluminum so after many on and offs, the bipod started to pull that aluminum hole open 2) the mount had issues staying put. I originally loctited it but after it came loose later on I pulled the lock nuts out of one of my BCM rails and switched the nuts, this seemed to work. They may have fixed all this as I had an extensive conversation with them about the issues.

Problem #1 caused me to contact odin works and they replaced the mount which I gave away and moved on to the Noveske bipod mount which works perfect with keymod - http://www.noveske.com/products/trx-sling-stud-bi-pod-mount. Odin works CS was great other than the fact the mount sucked and needs a redesign.

[Fatorangecat]

Is it the odin works mount with the harris bipod adapter? If so, just as a data point - I had that mount and had two problems 1) where the bipod mounts it does not have a lot of connective metal which is also aluminum so after many on and offs, the bipod started to pull that aluminum hole open 2) the mount had issues staying put. I originally loctited it but after it came loose later on I pulled the lock nuts out of one of my BCM rails and switched the nuts, this seemed to work. They may have fixed all this as I had an extensive conversation with them about the issues.

Problem #1 caused me to contact odin works and they replaced the mount which I gave away and moved on to the Noveske bipod mount which works perfect with keymod - http://www.noveske.com/products/trx-sling-stud-bi-pod-mount. Odin works CS was great other than the fact the mount sucked and needs a redesign.

My experience with the Odin Works mount is completely different. Rock solid mount and I frequently load the bipod but you may shoot more than I do.

[HansTheHobbit]

I actually don't think he wants help.

I think he's here to proclaim/declare/allege that keymod stuff is falling off of his rifle in an unadulterated and unprovoked manner (while not being used,) and furthermore to connect, network, and discuss said phenomena with similarly-afflicted people.

I think it would be awesome for there to be a support group somewhere for all the people that get white knuckles and strained forehead veins when they throw themselves into fifty page threads attempting to proclaim a victor to this 'war' that's being waged inside their heads. I'm not accusing the OP of being one of 'those people' but I can feel the ground shaking already. ;)

All I'm asking is that people stay on topic, which is that I'm having problems with a certain kind of keymod mount. If you'll actually read the OP I go into great detail about how I'm NOT having anything but wild success with a different type of mount. In short, this thread is about the fine differences between keymod mount designs in terms of how they place the indexing tab, not about the keymod system in general, which I like a lot. I'm not some yahoo putting his shit on backwards, which should be pretty obvious to anyone who actually paid any attention to what I said in the OP.

[HansTheHobbit]

Is it the odin works mount with the harris bipod adapter? If so, just as a data point - I had that mount and had two problems 1) where the bipod mounts it does not have a lot of connective metal which is also aluminum so after many on and offs, the bipod started to pull that aluminum hole open 2) the mount had issues staying put. I originally loctited it but after it came loose later on I pulled the lock nuts out of one of my BCM rails and switched the nuts, this seemed to work. They may have fixed all this as I had an extensive conversation with them about the issues.

Problem #1 caused me to contact odin works and they replaced the mount which I gave away and moved on to the Noveske bipod mount which works perfect with keymod - http://www.noveske.com/products/trx-sling-stud-bi-pod-mount. Odin works CS was great other than the fact the mount sucked and needs a redesign.

Thanks for letting me know. I was pretty taken aback by how delicate the Odin Works mount was. Mine is holding up so far, besides the aforementioned episode of it coming loose, but I haven't used it much.

I would totally write this whole thing off as Odin Work's fault if it weren't for the flashlight mount coming loose, as it's made by Vltor. Considering they invented keymod, I figure their stuff should be pretty much fool proof. And I would still be willing to write both off as just being out of spec, but not for the fact that both have the same basic design, with the indexing tabs pushing the foot into its slot, as opposed to pulling them forward, like with the mounts I'm having no issues with.

[nolt]

All I'm asking is that people stay on topic, which is that I'm having problems with a certain kind of keymod mount. If you'll actually read the OP I go into great detail about how I'm NOT having anything but wild success with a different type of mount. In short, this thread is about the fine differences between keymod mount designs in terms of how they place the indexing tab, not about the keymod system in general, which I like a lot. I'm not some yahoo putting his shit on backwards, which should be pretty obvious to anyone who actually paid any attention to what I said in the OP.

I did read that, and I do think that there is value in the discussion.
I don't have any problems with the mounts that I have; but they all mount in the same fashion as the BCM QD slot mount which, to my understanding, is one of the ones that you have pretty much universal success with so far.

While I've read your descriptions of the other mounts and your descriptions aren't necessarily lacking or contradictory, it would enhance my understanding of the interface further to see a detailed pic of the mount and how the stationary retention part is positioned in relation to the screws and the orientation of the lugs on them. Something that my mind can orient into a keymod slot (also in my mind.)

It can be difficult to picture how the part fits in there and torques into place and pictures certainly help.
I do not think you are 'obligated' in any way to post pics of the part interfaces that you are having trouble with, but I do think it would enhance the discussion (and the quality of replies.)

JMO. I'm no keymod expert I'm just some douche on the internet (with some keymod stuff) that THINKS he knows what you're trying to describe but I'm not 100% positive so I'm kind of scratching my head because I've not encountered parts that interface exactly as I think you're describing.

[Rayrevolver]

Like I said, there's no way the mounts could be backwards. If that were the case, then they would have destroyed my rails, especially as tight as I torqued the screws this time around.

I had an issue with a KM sling mount. Vendor said if I over-torqued I could have stretched the nut or squashed the rail. From memory it said hand tight and then 1/8 of a turn or 18 in-lbs (or 25... can't remember).

Why don't you mount another known good keymod device in that same spot and see what happens? If it moves, then the rail may be out spec or was ruined by your gorilla torque.

[HansTheHobbit]

I did read that, and I do think that there is value in the discussion.
I don't have any problems with the mounts that I have; but they all mount in the same fashion as the BCM QD slot mount which, to my understanding, is one of the ones that you have pretty much universal success with so far.

While I've read your descriptions of the other mounts and your descriptions aren't necessarily lacking or contradictory, it would enhance my understanding of the interface further to see a detailed pic of the mount and how the stationary retention part is positioned in relation to the screws and the orientation of the lugs on them. Something that my mind can orient into a keymod slot (also in my mind.)

It can be difficult to picture how the part fits in there and torques into place and pictures certainly help.
I do not think you are 'obligated' in any way to post pics of the part interfaces that you are having trouble with, but I do think it would enhance the discussion (and the quality of replies.)

JMO. I'm no keymod expert I'm just some douche on the internet (with some keymod stuff) that THINKS he knows what you're trying to describe but I'm not 100% positive so I'm kind of scratching my head because I've not encountered parts that interface exactly as I think you're describing.

Here's an example of the setup that works for me. As you can see, the indexing tab goes into the next forward slot and is "pulling" the foot into its slot. This is the type that I'm having universal success with, that have one indexing tab that pulls. This is indicative of all the QD sling sockets I've ever seen to date.

http://cdn3.volusion.com/tdczj.otkbv/v/vspfiles/photos/V7-KM-QDSM-3.jpg?1432858492

Here's an example of one that "pushes" the foot, and note how the indexing tab actually shares the same slot.

http://www.megaarms.com/wp-content/gallery/maten_accessories_keymodrails/img_4624.jpg

This next one is very similar to the odin works bipod adapter, almost identical in fact, in that it has one indexing tab in the center of two screws, such that it pulls one and pushes the other.

http://cdn3.volusion.com/j4enh.r2en5/v/vspfiles/photos/PWS-5KMRS5S1-3.jpg?1447479649

This is the Vltor millennium mount that I've had the most trouble with. It's unique from most other keymod mounts in that both screws have their own indexing tab that shares the same slot. You can imagine two indexing tabs behind each screw on the backside.

https://www.vltor.com/wordpress/wp-content/uploads/2015/02/KM-SLM.png


The overwhelming trend I'm seeing is that there's really no standard doctrine in how the indexing tabs are placed. They seem to just get stuck wherever it's most convenient to the design, without any thought as to how it will effect the performance. There's also no standard for how many indexing tabs there should be. Some mounts have an indexing tab for each screw, while some have a single tab for four or five screws. My opinion as of right now is that only one indexing tab is needed for a mount of any length, but that it must be placed forward of the screws, so that it's pulling them into their slots. I think having multiple indexing tabs, or alternately having indexing tabs creating forces in different directions, is somehow causing certain mounts to fail.

[HansTheHobbit]

I had an issue with a KM sling mount. Vendor said if I over-torqued I could have stretched the nut or squashed the rail. From memory it said hand tight and then 1/8 of a turn or 18 in-lbs (or 25... can't remember).

Why don't you mount another known good keymod device in that same spot and see what happens? If it moves, then the rail may be out spec or was ruined by your gorilla torque.

The mounts were falling off before I torqued them on tighter. I've also been using a fat wrench to make sure I don't go overboard. I think it would be impossible to overtorque keymod stuff without ruining the allen head. I could see the torx head screws maybe, but the allen ones start to fail after about 30 inch pounds or so, at least in my experience.

ETA: I went back and checked my current torque settings, which were at about 20-25 pounds. I had started out at around 15, which came loose. I know the FAT wrench isn't the most accurate torque driver on the market, but I'll bet it's within two inch pounds. More than accurate enough for this application, especially since people use them for mounting scopes all the time, including myself.

[Uprange41]

There are pretty consistent KeyMod manufacturers that work for guys, I wish I understood why people deviate.

[HansTheHobbit]

There are pretty consistent KeyMod manufacturers that work for guys, I wish I understood why people deviate.

How would you consider Vltor to be "deviating?" They freaking invented keymod for crying out loud. Not to mention that the whole reason Vltor released keymod into the public domain was to encourage other manufacturers to make accessories for their rails.

[nolt]

I wonder if some of the designs can make the part 'feel' like it's in place and ready to be tightened when it's not?

I also wonder if some of them are off just a few thousandths and do not properly hold when tightened.

It would seem like either arrangement (tab in front or back) would work if they are oriented and installed correctly and also rigid enough (polymer rails etc) to not flex and deform themselves out of position.

I also have a couple of the BCM QD mounts as you posted and have found them to work perfectly.

My Arisaka inline keymod scout mounts are (I'm almost positive) similar to that PWS design you posted with the knob/tab in between the two keymod nuts, and I've never had them get loose at all. I've moved them around a bit more than the BCM QD mounts.

Obviously I'm a statistically insignificant sample size.

I would guess that problems with designs are more related to measurements than placement. Especially metal parts.

[Uprange41]

How would you consider Vltor to be "deviating?" They freaking invented keymod for crying out loud. Not to mention that the whole reason Vltor released keymod into the public domain was to encourage other manufacturers to make accessories for their rails.

How many guys do you know that are running VLTOR KeyMod parts, vs. BCM, Arisaka, IWC, etc?

I don't care who invented what, there's shit that you can see works well on a consistent basis, and then there's everything else that you'd assume works well.

[HansTheHobbit]

I wonder if some of the designs can make the part 'feel' like it's in place and ready to be tightened when it's not?

I also wonder if some of them are off just a few thousandths and do not properly hold when tightened.

It would seem like either arrangement (tab in front or back) would work if they are oriented and installed correctly and also rigid enough (polymer rails etc) to not flex and deform themselves out of position.

I also have a couple of the BCM QD mounts as you posted and have found them to work perfectly.

My Arisaka inline keymod scout mounts are (I'm almost positive) similar to that PWS design you posted with the knob/tab in between the two keymod nuts, and I've never had them get loose at all. I've moved them around a bit more than the BCM QD mounts.

Obviously I'm a statistically insignificant sample size.

I would guess that problems with designs are more related to measurements than placement. Especially metal parts.

I always make sure that the indexing tab is firmly butted up against its respective slot before I start tightening. Even if it weren't, though, the feet would push it into position as soon as you started torquing the screws, so long as the indexing tab was actually in the slot. BTW, failure to have the indexing tab seated in the slot would probably result in ruining the rail. I also push down on the mount as I'm doing the initial tightening just to make sure it doesn't jump out of its slot, and after the slack is taken up it just doesn't have anywhere to go after that.

[tonyxcom]

If you aren't using thread locker of some kind this is user error.

Also, there is no pushing or pulling happening with these index tabs respective of their location of the fastener. They are just recoil lugs, they prevent the fasteners from sliding during recoil. It doesn't matter where they are located, they do the exact same thing - prevent sliding.

[HansTheHobbit]

How many guys do you know that are running VLTOR KeyMod parts, vs. BCM, Arisaka, IWC, etc?

I don't care who invented what, there's shit that you can see works well on a consistent basis, and then there's everything else that you'd assume works well.

Lots of people "run" Vltor keymod stuff. In the early days, that's all there was. Vltor also produced a lot of stuff used by other shops, Noveske for one. You mentioned BCM; well, they've hired the guy from Vltor. I would consider IWC to be "deviating" as you say.

[HansTheHobbit]

If you aren't using thread locker of some kind this is user error.

Also, there is no pushing or pulling happening with these index tabs respective of their location of the fastener. They are just recoil lugs, they prevent the fasteners from sliding during recoil. It doesn't matter where they are located, they do the exact same thing - prevent sliding.

Loctite isn't supposed to be necessary. Last I heard, Vltor and others were actually discouraging it. As for the tabs, or recoil lugs or whatever you want to call them, they are not just for recoil. They are loaded all the time to a certain extent. You can see this if you push the mount forward while you're installing it. As you tighten the screws, the mount will actually move to the rear until the tabs stop it.

[tonyxcom]

Loctite isn't supposed to be necessary. Last I heard, Vltor and others were actually discouraging it. As for the tabs, or recoil lugs or whatever you want to call them, they are not just for recoil. They are loaded all the time to a certain extent. You can see this if you push the mount forward while you're installing it. As you tighten the screws, the mount will actually move to the rear until the tabs stop it.

There is nothing in the design that suggests it isn't necessary unless the nuts had helicoils in them.

If you think the lugs are pushing or pulling the mounts as you tighten them, that pretty much confirms you don't understand how Keymod is designed to work. So you are either here for help, or you are here to convince people you don't need it. Which is it?

BTW, I have used accessories on NSR and KMR rails that have the recoil lug fore and aft of the fastener and use Locktite. NONE of them have come loose under use, much less leaning on your safe as you describe.

[GH41]

I have BCM, KAC, HSP and Samson accessories. None of the indexing tabs look the same but they all serve the same purpose. They prevent the accessory from moving to the rear and the nut from disengaging the KM slot. It makes NO difference if the tab hooks the rear of the slot ahead of the nut or buts the back of the slot behind the nut. The tightness of the screw has NOTHING to do with the fitting sliding back and forth. In the case of my KAC handstop both the nut and tab reside in a single slot with a single nut and screw. I understand that finding a camera, taking the stuff off to snap a picture and uploading it is more trouble than you think it is worth to help you diagnose your problem. I still think your nuts are on backward but without a picture of your stuff I cannot prove it. How about a simple test that won't involve a lot of effort on your part... Loosen the screws in the Odin mount about 3/4 turn... You should NOT be able to move the mount to the rear with the screw slightly loose. If it moves you probably have the mount on backwards. The toe of the nut always faces forward but that doesn't mean it was installed properly by the manufacturer. The orientation of the nut doesn't indicate the direction of the mount if backwards. A picture would help a lot.

[HansTheHobbit]

There is nothing in the design that suggests it isn't necessary unless the nuts had helicoils in them.

If you think the lugs are pushing or pulling the mounts as you tighten them, that pretty much confirms you don't understand how Keymod is designed to work. So you are either here for help, or you are here to convince people you don't need it. Which is it?

BTW, I have used accessories on NSR and KMR rails that have the recoil lug fore and aft of the fastener and use Locktite. NONE of them have come loose under use, much less leaning on your safe as you describe.

This may be the root of my problem. One of the mounts I'm having trouble with loads the tab when you tighten it, and I had always assumed that was how it was supposed to work. I just checked a BCM rail segment to see if it did the same thing, and it doesn't. If you're right about the tabs not being loaded, then that could very well be the issue.

[tonyxcom]

if you orient the rail like a table, the keymod accessory should lay flush on with the rail without any torque at all. If it doesn't, something is clearly amiss.

[HansTheHobbit]

if you orient the rail like a table, the keymod accessory should lay flush on with the rail without any torque at all. If it doesn't, something is clearly amiss.

Yes, it does lay flush. What I'm saying is that once it's in position, there's some play back and forth. On one of the mounts, as I tighten the screws, I can see the mount move back until the tab is pressed up against its slot. Like I said, I assumed this was normal, but if what you're saying is true then it isn't. It would suggest that the foot isn't shaped right and is applying uneven pressure, causing it to slip. Like I said, I just tried a BCM rail segment, watching it very carefully, and it doesn't do it.

[tonyxcom]

What I'm saying is that once it's in position, there's some play back and forth.

Then its possible the mount, nuts, or both are backwards - or the machining/design of the accessory is out of spec.

As has been said before, a picture really is worth a thousand words here.

[HansTheHobbit]

Then its possible the mount, nuts, or both are backwards - or the machining/design of the accessory is out of spec.

As has been said before, a picture really is worth a thousand words here.

The Vltor Millennium mount is impossible to get backwards, and the nuts are captured. You literally cannot unscrew them from the allen screws. The nuts are captured in the mount, and the screws are captured in the nuts so that you can only unscrew them just barely far enough to slide it into position.

[tonyxcom]

Can you show me the bottom of that mount? I can't find one online and I shouldn't even have to search for one. Can you show me how you are attaching it to your rail?

Without pictures of both of those things there will be more pages of speculation and no definitive solutions.

Good Luck in either case.

[HansTheHobbit]

Can you show me the bottom of that mount? I can't find one online and I shouldn't even have to search for one. Can you show me how you are attaching it to your rail?

Without pictures of both of those things there will be more pages of speculation and no definitive solutions.

Good Luck in either case.

Thanks for the help, but I think we've pretty much exhausted all the possible solutions. I emailed Vltor to get an exact torque spec, so my plan at this point is to retorque everything to their spec and see what happens. I will also be using loctite from here on out. I don't know that it will help, but it certainly can't hurt anything at this point.