View Full Version : URXII loose. How do I tighten it?
My URXII rail has begun rotating about 1/4" to the right, which throws off my irons. I can't see any way to re-tighten it, however. For the moment, I've moved my optic mount ahead one rail space to hold the forearm from rotating, and it seems to work, but I'd rather fix the problem itself.
You should stop shooting it, the barrel will also be loose.
Is it a KAC rifle or did you have a shop install the rail on your rifle? You need special tools to install it correctly, it's not something you can fix at home.
Belmont31R
09-08-11, 11:57
Needs to be fixed. Barrel nuts are one time use so you need a new one, and have it redone.
Don't shoot it that condition because the barrel is going to be loose, too.
The KAC URX rail is expensive and the wrench to install is as well. I implore you to contact KAC and see if they can fix it or recommend someone. If you take it to the local butcher you risk ending up with hamburger meat and not prime rib.
First time I've heard of this happening. Is this a KAC rifle or a upper built up with a URX? If so, who installed it?
Belmont31R
09-08-11, 13:03
I had one loosen up on me. Not a factory KAC gun but was put together by an at the time KAC employee on his own.
Yes it needs to go to someone who knows what they are doing. I recommend either Gun Gallery in FL, MSTN or Lawmens Shooter Supply. All have the tools and experience to get this fixed. If its a factory gun contact KAC.
jonconsiglio
09-08-11, 13:04
The URX II is not rotation limited and you're on your way to a dangerous situation. Do NOT have someone local try to work on it unless they install and uninstall URX rails regularly since the barrel nut is a proprietary part and needs the $200 or $250 wrench to work on it.
This is part of the reason I traded one of my SR15's and why I ordered a RIS II to replace the URX II on my remaining sr15. Something like that happens while on a trip or during a class, it's most likely not going to be fixed until it's sent somewhere unlike a standard rail and barrel nut.
By any chance did you have the muzzle device replaced?
Magic_Salad0892
09-08-11, 15:50
Get in contact with Casey at Lawmens, he should be able to help you out.
Get in contact with Casey at Lawmens, he should be able to help you out.
Casey is now a KAC employee. I believe the new Lawmen's contact is Troy.
Magic_Salad0892
09-08-11, 15:57
Casey is now a KAC employee. I believe the new Lawmen's contact is Troy.
Here's hoping Troy is just as helpful.
First time I've heard of this happening. Is this a KAC rifle or a upper built up with a URX? If so, who installed it?
Pretty common.
C4
Casey is now a KAC employee. I believe the new Lawmen's contact is Troy.
Correct. However, I don't think Lawmens will be doing rail installs any longer. I've been told that their gunsmith is no longer there. If its a KAC complete upper, call KAC. If not, I'd contact Neil at Gun Gallery. I'd recommend Grant too, but I don't think he has the time these days. ;-)
Robb Jensen
09-08-11, 20:34
If you're near Northern VA I own the KAC alignment block and URX wrenches as well. I own two URX II rails and two URX III rails myself.
If you're near Northern VA I own the KAC alignment block and URX wrenches as well. I own two URX II rails and two URX III rails myself.
Robb, I didn't realize you guys did URX work as well. Any URX III's in stock?
Robb Jensen
09-08-11, 21:35
Robb, I didn't realize you guys did URX work as well. Any URX III's in stock?
We don't sell nor stock KAC rails, I'm just capable of working on them.
Pretty common.
C4
yikes...does anyone have the install instructions for the new URX II, as the only one I ever seen is with the old nut and tube wrench. I believe the newer nut has a lower torque? Any pointers from the pros who have done many installs to minimise this happening?
yikes...does anyone have the install instructions for the new URX II, as the only one I ever seen is with the old nut and tube wrench. I believe the newer nut has a lower torque? Any pointers from the pros who have done many installs to minimise this happening?
I have installed many of them. You basically have to red loctite the barrel nut onto the receiver. I think where people make an error is not FULLY degreasing the receiver and the nut OR shooting the gun too soon (not letting the loctite dry).
IMHO, this rail is much more likely to come loose than most other rail on the market. So when getting one installed, I would suggest the factory OR an armorer that will fix it if/when it comes loose.
C4
We don't sell nor stock KAC rails, I'm just capable of working on them.
And doing a kick-ass job on them.
I have installed many of them. You basically have to red loctite the barrel nut onto the receiver. I think where people make an error is not FULLY degreasing the receiver and the nut OR shooting the gun too soon (not letting the loctite dry).
IMHO, this rail is much more likely to come loose than most other rail on the market. So when getting one installed, I would suggest the factory OR an armorer that will fix it if/when it comes loose.
C4
Noted.
Thanks for the install tip C4
Thanks for all the responses.
It's a BCM built 11.5" upper receiver that I bought directly from BCM. I installed a BattleComp on it last year, but had to remove it and have it replaced. I re-installed the replacement BC 2.0 with a crush washer, and timed it per the instructions I found in a thread on here.
I had no idea it was dangerous to shoot. I just figured the rail needed to get torqued back down. Luckily I haven't had time to go to the range since I noticed it. I've only put three mags through it since I installed the BC 2.0.
Will BCM repair it, or should it go to a third party?
A few questions, if I may.
1. How long have you had said upper?
2. Was it loose when you received it? Did you check?
3. Is it possible that it happened after you installed the BC?
4. How did you secure the upper when you installed the BC?
Thanks for all the responses.
It's a BCM built 11.5" upper receiver that I bought directly from BCM. I installed a BattleComp on it last year, but had to remove it and have it replaced. I re-installed the replacement BC 2.0 with a crush washer, and timed it per the instructions I found in a thread on here.
I had no idea it was dangerous to shoot. I just figured the rail needed to get torqued back down. Luckily I haven't had time to go to the range since I noticed it. I've only put three mags through it since I installed the BC 2.0.
Will BCM repair it, or should it go to a third party?
does anyone have the install instructions for the new URX II, as the only one I ever seen is with the old nut and tube wrench.
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX1.jpg
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX2.jpg
Thanks for all the responses.
It's a BCM built 11.5" upper receiver that I bought directly from BCM. I installed a BattleComp on it last year, but had to remove it and have it replaced. I re-installed the replacement BC 2.0 with a crush washer, and timed it per the instructions I found in a thread on here.
I had no idea it was dangerous to shoot. I just figured the rail needed to get torqued back down. Luckily I haven't had time to go to the range since I noticed it. I've only put three mags through it since I installed the BC 2.0.
Will BCM repair it, or should it go to a third party?
I don't understand how changing a muzzle device would cause the rail to loosen.
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX1.jpg
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX2.jpg
From what I know from talking to the factory guys, they do NOT use blue loctite. I wouldn't either (as it is NEVER going to make it).
C4
Belmont31R
09-10-11, 09:22
Thanks for all the responses.
It's a BCM built 11.5" upper receiver that I bought directly from BCM. I installed a BattleComp on it last year, but had to remove it and have it replaced. I re-installed the replacement BC 2.0 with a crush washer, and timed it per the instructions I found in a thread on here.
I had no idea it was dangerous to shoot. I just figured the rail needed to get torqued back down. Luckily I haven't had time to go to the range since I noticed it. I've only put three mags through it since I installed the BC 2.0.
Will BCM repair it, or should it go to a third party?
The URX is a bit different in that the barrel nut does not thread onto the actual receiver but the inside of the rail. If the rail is loose the barrel is loose, too. The rail is what gets threaded onto the receiver, and then once the barrel nut is installed is what keeps the rail from moving and the barrel in place.
I know there are different types of Loctite but its been my impression certain ones will burn up or at least be severely weakened through heat, and over time with the heating and cool down of shooting. I would think something like RockSet (sp?) would be better. I know Surefire and KAC both supply it for use with muzzle devices.
The URX is a bit different in that the barrel nut does not thread onto the actual receiver but the inside of the rail. If the rail is loose the barrel is loose, too. The rail is what gets threaded onto the receiver, and then once the barrel nut is installed is what keeps the rail from moving and the barrel in place.
I know there are different types of Loctite but its been my impression certain ones will burn up or at least be severely weakened through heat, and over time with the heating and cool down of shooting. I would think something like RockSet (sp?) would be better. I know Surefire and KAC both supply it for use with muzzle devices.
I tried Rocksett and it did not hold. :(
C4
Belmont31R
09-10-11, 09:59
Hmm.. Ive had pretty good results with Rocksett but never tried it on a barrel nut.
Loctite has a few different high temp thread lockers.
2620 Red Up High Temp to 650F
266 Orange High Strength High Temp
272 Red High Strength Fast Curing High Temp
Have you tried any of these?
Hmm.. Ive had pretty good results with Rocksett but never tried it on a barrel nut.
Loctite has a few different high temp thread lockers.
2620 Red Up High Temp to 650F
266 Orange High Strength High Temp
272 Red High Strength Fast Curing High Temp
Have you tried any of these?
Rocksett works well on small threads, but does not seem to work as well on coarse threads.
When we did URX installs, we used Red Loctite. I had about 50/50 luck with this.
C4
I don't understand how changing a muzzle device would cause the rail to loosen.
The installer used a upper rec. block VS. a barrel block.
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX1.jpg
http://i757.photobucket.com/albums/xx213/JimmyZNY/URX/URX2.jpg
thank you.
EzGoingKev
09-10-11, 13:08
If the Red isn't getting it done then I would suggest trying Loctite 680.
jonconsiglio
09-10-11, 13:12
A few questions, if I may.
1. How long have you had said upper?
2. Was it loose when you received it? Did you check?
3. Is it possible that it happened after you installed the BC?
4. How did you secure the upper when you installed the BC?
That's pretty much what I was asking a while back. I'm still curious about this.
Dos Cylindros
09-10-11, 13:25
These are all reasons why I chose to sell my BCM BFH upper with URX rail. I was not fond of the attachment method or what appeared to be a very fragile folding front sight set up. I am much happier with my BCM middy with standard FSB and Centurion Arms C4 9" rail. I believe it is a more durable setup.
jonconsiglio
09-10-11, 14:03
I've sold two of my three URX II's for similar reasons. Once my 12" RIS II gets here, I'll be selling my last URX II.
A few questions, if I may.
1. How long have you had said upper?
About a year. I got it last fall from BCM.
2. Was it loose when you received it? Did you check?
I don't recall it ever being loose like this. I checked it over pretty thoroughly.
3. Is it possible that it happened after you installed the BC?
After the second BC, perhaps since I've only got a few mags through it. The thing is, the rail is turning in the opposite direction as the brake is installed. Not sure that makes any difference, though.
4. How did you secure the upper when you installed the BC?
I used a Brownell's upper receiver block secured in a vise. I surmise after reading this thread that that might have not been a good idea.
Has this been known to happen when installing muzzle devices on URXs? I am currently saving for my KAC E3 upper, so if this is a problem with the design, I might rethink things a little.
Has this issue been resolved with the newer hex rails? I understand and anti rotation design was supposed to be in the works.
Well, this has certainly been an eye opening thread for me. I'm completely rethinking purchasing one of these rails to replace a KAC mid length FF on my 16" Centurion barrel carbine.
I've never had a problem with it, and it stays on the gun!
Has this been known to happen when installing muzzle devices on URXs? I am currently saving for my KAC E3 upper, so if this is a problem with the design, I might rethink things a little.
Hasn't been a problem with three of mine.
Has this issue been resolved with the newer hex rails? I understand and anti rotation design was supposed to be in the works.
Anti rotation was built into the QD sling attachment points, not the rail itself.
Very interesting thread. I have been wanting an SR15 E3 upper since I already have a KAC SR15 lower. This might make me rethink this purchase. I have seen pics of the M110 in the sandbox with the front flip-up sight missing and that always made me question the durability of the design. I understand that any rail-mounted sight can be broken if it takes a hard enough hit, but another one can be mounted easily while the integrated design of the E3 sight wouldn't be possible. I guess a rail mount sight could be mounted on the remaining rail though. I really like the Centurion rails and might have to go with a lightweight barrel upper with one of those instead of the KAC.
ARKAR
Robb Jensen
09-11-11, 08:30
I use blue and sometimes red, if using blue you use quite a bit more. Rocksett doesn't seem to work very well on aluminum nor course threads. I think this is due to the expansion and contraction rate of aluminum.
Ok, here's my concern/question:
Is the appropriate method for changing muzzle devices to use a barrel block? If so, how do I do that with a URX installed? I will be installing an AAC mount when my can gets approved, and then again if BC comes out with an AAC-compatible brake. Does this mean I'll have to send the whole upper out to a KAC-equipped smith to have the brake installed?
That's discouraging.
Per the TM it is supposed to be performed with a barrel block and vise.
Ok, here's my concern/question:
Is the appropriate method for changing muzzle devices to use a barrel block? If so, how do I do that with a URX installed? I will be installing an AAC mount when my can gets approved, and then again if BC comes out with an AAC-compatible brake. Does this mean I'll have to send the whole upper out to a KAC-equipped smith to have the brake installed?
That's discouraging.
Ok, here's my concern/question:
Is the appropriate method for changing muzzle devices to use a barrel block? If so, how do I do that with a URX installed? I will be installing an AAC mount when my can gets approved, and then again if BC comes out with an AAC-compatible brake. Does this mean I'll have to send the whole upper out to a KAC-equipped smith to have the brake installed?
That's discouraging.
When I installed my battlecomp 2.0 on to my SR-15, I just made a barrel block out of wood and clamped the barrel tightly in my vice.
I just took two small blocks of 2x4, put a strip of cardboard between them to space them out, then used a 5/8'' drill to make a hole. Then threw away the cardboard, lined the wood channels with one strip of duct tape, clamped the barrel TIGHT. It worked perfectly, didn't scratch anything and didn't cost anything. The purpose of the cardboard was to ensure that when clamping on the barrel, the force goes on the barrel rather than one wood block on the other.
There isn't much barrel sticking out to clamp on to, so it helped to have a vice with 2 axis rotation. You have to clamp at an angle.
Very interesting thread. I have been wanting an SR15 E3 upper since I already have a KAC SR15 lower. This might make me rethink this purchase. I have seen pics of the M110 in the sandbox with the front flip-up sight missing and that always made me question the durability of the design. I understand that any rail-mounted sight can be broken if it takes a hard enough hit, but another one can be mounted easily while the integrated design of the E3 sight wouldn't be possible. I guess a rail mount sight could be mounted on the remaining rail though. I really like the Centurion rails and might have to go with a lightweight barrel upper with one of those instead of the KAC.
ARKAR
Exactly and this is one of the major drawbacks of the URX.
Honestly, it was enough of a drawback that I opted not to get a KAC upper at this time. Maybe later on I will get one when they come out with some new rails, but I'm in no hurry right now. I don't like the idea of being dependent on a smith for simple rail installation and removal, and I like the idea of buying $500 in proprietary tools even less. I've been planning on getting an E3 upper for about 8mos now, and yesterday I decided to go with a BCM 16" mid upper with a 13.8" Troy Alpha rail to go on my IWS lower. It was half the price of the KAC and has mostly everything I was looking for. I can spend the rest of the cash on a T-1 and ammo.
I'll give it a shakedown at my first carbine class in Oct.
By the way, I contacted BCM about the problem, related the situation and they offered to repair it free of charge. That's what sealed the deal on buying the new upper. Great company with great CS.
AnimalMother556
09-14-11, 19:55
That's pretty much what I was asking a while back. I'm still curious about this.
I was considering having my urx replaced as I'm not fond of the front sight as it seems flimsy and limits mounting options. Are there any other rails that can be used with an SR15 barrel and gas block?
IMHO the URX is overrated.
1. It has the flip up sight which limits mounting options of lights or sighting devices on the top rail.
2. It is one of the most expensive rails on the market and you have to get another $500 worth of tools to install it or send it off to be installed.
3. No anti rotation sling sockets.
4. It is on the heavy side of the weight spectrum
5. The secureness of the mounting and barrel nut system has been in question from day one.
The only thing it has going for it is you can remove the bottom rail for cleaning.
I can buy a Samson rail that has none of these issues for half the price (after installation is factored in) and I can remove the bottom rail.
Belmont31R
09-14-11, 22:22
I think the DD RIS II is the best rail on the market but wish it was offered in more lengths. DD seems to be WAY behind on just about everything, though.
FWIW I have over 17k now through my SR15 and the rail is still doing fine. I do not like the non rotation limiting sling swivels, and use a DD bolt on which is rotation limited. My EMC has right about 3300 now and has done fine, too.
I can see where the built in front sight could be broken off, and what a pain it would be to get fixed. My guess is a trip to the factory for a few hundred bucks. Id rather just a straight rail section or make it beefier. But looking at the options a bolt on BUIS would be the better choice.
Robb Jensen
09-14-11, 22:35
URXIII have stops in the QD sockets. Anyone with ACTUAL experience with them would know this
I wish I had weighed of my URXIIIs before installation, they are very light. Very similar in weight to a 13" Troy/VTAC TRX with a Magpul MOE front sight.
Belmont31R
09-14-11, 22:52
I would rather put on a bolt on QD cup than have them place on the rail in set points.
But its nice they finally got them limited.
AnimalMother556
09-15-11, 16:00
I'd still like to know if there would be any issues trying to use an SR15 barrel with other rail systems or if it would be easier or more cost-effective to just sell the upper and start over. I rather like the improved bolt though as well as the gas system.
Has anybody made the swap?
IMHO the URX is overrated.
1. It has the flip up sight which limits mounting options of lights or sighting devices on the top rail.
Limits installation of items exactly where the front sight would go, sure. I suppose that leaves out a X300, but not really because you still have rail there; I have seen a Stickman photo with a X300 in that position and a folding front sight behind it. It locks and isn't going anywhere (may rattle slightly, but on a light who cares?). It also saves you from having to buy a front sight. It's debatable how important access to the front sight is if you're running optics as a primary. I imagine this will be based largely on personal preference.
2. It is one of the most expensive rails on the market and you have to get another $500 worth of tools to install it or send it off to be installed.
That's a little extreme. Sure, it's expensive to buy parts to work on it yourself. I sent off an upper to a KAC dealer in FL to get rebarreled, FSB shaved, URX II installed (bought the URX II from them), and shipped back to me for the grand total of $400. My RIS II cost $380 from Rainier Arms for just the rail (and that was a good price for the rail shipped).
3. No anti rotation sling sockets.
No argument here. But you get 4 or 5 of them.
4. It is on the heavy side of the weight spectrum
That's a new one. My URX II rifle length is light as a feather.
5. The secureness of the mounting and barrel nut system has been in question from day one.
Perhaps. Can't comment on this other than saying some anti-rotation tabs would have been a nice touch.
The only thing it has going for it is you can remove the bottom rail for cleaning.
I will say that it is one of the most accurately machined rails I have used. I have used the RIS II, Centurion C4, and the URX II and the latter is the only one whose Picatinny rails line up perfectly with the upper. The C4 is about .5mm low and the bottom edges of the RIS II don't match quite as well. It also has built-in heat shields (I noticed the difference between my RIS II even with gloves--both after the same number of rounds). Whether or not all of its features imply benefits > costs or vice versa is up to the end user.
I can buy a Samson rail that has none of these issues for half the price (after installation is factored in) and I can remove the bottom rail.
Samson and KAC aren't in the same class.
In red.
I agree very much on the cost issue. You aren't only buying a rail with the URXII. It includes a front sight and the qd sling pockets in five locations. Add all that up and it's really a great deal!
I'm probably gonna end up with a KAC SR15E3 upper. They are just too sexy. Like I said, I have a lower, just need to get an upper.
ARKAR
http://i82.photobucket.com/albums/j248/87228/P8100550.jpg
Put a rail panel next to the QD socket, and voila! Anti-rotation.
IMHO the URX is overrated.
1. It has the flip up sight which limits mounting options of lights or sighting devices on the top rail.
2. It is one of the most expensive rails on the market and you have to get another $500 worth of tools to install it or send it off to be installed.
3. No anti rotation sling sockets.
4. It is on the heavy side of the weight spectrum
5. The secureness of the mounting and barrel nut system has been in question from day one.
The only thing it has going for it is you can remove the bottom rail for cleaning.
I can buy a Samson rail that has none of these issues for half the price (after installation is factored in) and I can remove the bottom rail.
A few corrections:
1) a personal preference, which can be remedied by mounting whatever you want over the front sight.
2) the URX III can be had for under $300, including a front sight.
3) wrong - URX III has rotation limited QD sockets
4) weight - the RIFLE length URX III is 13 oz. This includes a front sight. A comparable RISII is 16 oz. without accounting for the front sight.
5) in spite of the discussion in this thread, my URX rails have never given me any trouble over thousands of rounds. The OP had a problem with a rail installed by BCM & they are going to fix it. It has not been determined if it came loose due to design or incorrect installation. There are a ton of SR15's out there these days with factory installed URX rails. They don't seem to be failing at the rates this thread would have you believe.
I am curious, how many rounds were on the gun when the rail came loose? What kind of shooting do you do with it? Does it see "hard use"?
I am curious, how many rounds were on the gun when the rail came loose? What kind of shooting do you do with it? Does it see "hard use"?
I've had it for about a year, but it's only had a few hundred rounds through it. I live in the city and didn't until just a couple months ago have anywhere that allows "rapid" fire.
I've had it for about a year, but it's only had a few hundred rounds through it. I live in the city and didn't until just a couple months ago have anywhere that allows "rapid" fire.
Interesting. I might understand the rail coming loose after some abuse or being struck, but am surprised to hear it loosened up after light use. Sounds like an installation issue. I'm sure BCM will get you squared away in no time.
A few corrections:
1) a personal preference, which can be remedied by mounting whatever you want over the front sight.
2) the URX III can be had for under $300, including a front sight.
3) wrong - URX III has rotation limited QD sockets
4) weight - the RIFLE length URX III is 13 oz. This includes a front sight. A comparable RISII is 16 oz. without accounting for the front sight.
5) in spite of the discussion in this thread, my URX rails have never given me any trouble over thousands of rounds. The OP had a problem with a rail installed by BCM & they are going to fix it. It has not been determined if it came loose due to design or incorrect installation. There are a ton of SR15's out there these days with factory installed URX rails. They don't seem to be failing at the rates this thread would have you believe.
I am curious, how many rounds were on the gun when the rail came loose? What kind of shooting do you do with it? Does it see "hard use"?
1. The flip up front sight prevents you from mounting a laser sighting device at the end of the rail as this part is not rigid and you can't hold a zero. Saying you get a free front sight with the cost of the rail is also BS. If it came with a clamp on front sight that the user puts where they want, then you point is valid.
2. That doesn't negate the fact I have to buy tools that are expensive and not easily available.
3. The URX2 does not have anti rotation sockets. I am well aware version 3 does.
4. The URX2 weighs 1 lb 1.2 oz according to KAC's website for the 10" model. Most rails in this class weigh between 12oz and 16oz. I'm talking full railed handguards here. Not tube style stuff with bolt on rails.
5. Red loctite should not have to be used to secure any rail or any firearm part for that matter that could have to be removed for service. Several other people in this thread have made comments to this.
I'm not saying it is a bad rail. I wouldn't have a problem with using it. It just isn't all that great for the mount of money and work you have expend to have it.
1. The flip up front sight prevents you from mounting a laser sighting device at the end of the rail as this part is not rigid and you can't hold a zero. Saying you get a free front sight with the cost of the rail is also BS. If it came with a clamp on front sight that the user puts where they want, then you point is valid.
2. That doesn't negate the fact I have to buy tools that are expensive and not easily available.
3. The URX2 does not have anti rotation sockets. I am well aware version 3 does.
4. The URX2 weighs 1 lb 1.2 oz according to KAC's website for the 10" model. Most rails in this class weigh between 12oz and 16oz. I'm talking full railed handguards here. Not tube style stuff with bolt on rails.
5. Red loctite should not have to be used to secure any rail or any firearm part for that matter that could have to be removed for service. Several other people in this thread have made comments to this.
I'm not saying it is a bad rail. I wouldn't have a problem with using it. It just isn't all that great for the mount of money and work you have expend to have it.
I understand your points. I don't have a need to mount a laser, etc and don't run a light at 12:00. For my uses as a civi, it works well for me and I've had no issues with close to 8K rounds through two sr15s. I know that's not a high round count by some people's standards. To me the biggest issue is the tool needed. For an individual who wants to do their own work, it is certainly cost prohibitive. The cost for the rails has come down significantly over the last two years and is competitive with every one else on the market though.
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