View Full Version : URX 3.1 Install - Heads Up (SR-15 Owners)
After unsuccessfully removing my original rail from my gun myself (with the tool) I took it to my local gunsmith who has done this rail a couple times and is overall very competent in what he does....He ended up having to uninstall the gas block and flash hider. No matter how much heat we used he could not get the thing to budge. He ended up spinning the rail off with the barrel nut. It was a chore. The other ones he did not give him the same trouble. Maybe I got an abnormal amount of loctite on mine I don't know.
We then installed my 3.1 rail. It went on ok, but we noticed that the bottom corners of the gas block had very little to no clearance on the rail. Under normal fire the barrel movement would definatley cause the gas black to touch. Matter of fact if you grabbed the rail just right it would touch. I called Knights and just asked if their gas block that comes on the Sr-15 would work (not saying I had already done it). He said it would, but you would have to shave the corners, which is exactly what we had noticed. So he uninstalled the gas block again and shaved the corners down making sure both sides were uniform. He then sand blasted it and moly resined it the flat gray like it was before and re-installed everything. It now fits and looks great. Function tested great too.
So for anyone looking to get the new 3.1 to replace their standard rail be sure make sure you have the right tools necessary to modify you gas block otherwise it won't fit quite right....
so this goes for all gas blocks?
Does your rifle have the gas block with the two set screws?
My gas block has two taper pins instead of two set screws and the profile of the gas block is more consistent with other low profile gas blocks. There isn't an enlarged flat section on the bottom like you see on the KAC set screw ones.
Thanks for the heads up my man. At least it sounds like you have a plugged in gunsmith... those in themselves can be hard to find.
All of our new rifle systems released this year at SHOT will have a taper pin gas block that won't have any issues fitting under any of our rail systems. The slightly older Legacy SR-15's that had the dual set screws will require some slight modification to the bottom corners of the gas block to allow more clearance from the bottom of the rail.
Casey,
I assume that those of us wanting to send our URX-II equipped SR-15's back to the mothership to be retrofitted can have that taken care of?
Badness: This only refers to gas block on the SR15. I think other ones would be just fine. But cannot be 100% sure.
BP7178: Mine had the set screws. So you should be OK.
This guy (Casey?) from Lawmens (Knights?) that just posted in this thread was a cool guy to talk to and very helpful. He is the one I am referring to in my original post. Just an fyi.
Badness: This only refers to gas block on the SR15. I think other ones would be just fine. But cannot be 100% sure.
BP7178: Mine had the set screws. So you should be OK.
This guy (Casey?) from Lawmens (Knights?) that just posted in this thread was a cool guy to talk to. He is the one I am referring to in my original post. Just an fyi.
That's good to hear. I have a URX 3.1 sitting on my desk waiting for the barrel i want to come back "in-stock" :lol:
Casey,
I assume that those of us wanting to send our URX-II equipped SR-15's back to the mothership to be retrofitted can have that taken care of?
Unfortunately no, we are currently buried with trying to get all the stuff we released at SHOT out the door along with coming up with new products. That being said the dual set screw gas blocks are not causing any function issues with the guns, and if you're sending your upper off to have a URX installed I would think the gunsmith doing the work would be more than capable of trimming the corners of the gas block with little hassle.
Pics of the new GB for those who would like to compare to their own...
http://img850.imageshack.us/img850/1017/e3cqbsbr001.jpg
http://img856.imageshack.us/img856/6065/e3cqbsbr002.jpg
http://img268.imageshack.us/img268/3522/e3cqbsbr003.jpg
Weapon outfitters offers a $50 plus shipping gig for URX installations but an FSP grind costs $20 so I'm guessing if this is a problem you'd end up paying $70+Shipping in the end. Blehg?
That price isn't too bad I guess. Figure around $100-$120 buck with insured shipping?
My gunsmith said if he had to do this over again for someone he would charge around $150 to do the whole thing. It wasn't his favorite job lol.
I figure that much, yeah. Although with no FSP grind it would be even less.
Good to know, though! I've been wanting a URXIII for a while now but I want a cerakote job one it. It would be a strange task.
Robb Jensen
05-17-12, 18:24
Here's some pics of a set screw type KAC low pro that I re-profiled and refinished in blackish gray Norrells moly resin for my customer and installed a 12" URXIII rail.
http://img.photobucket.com/albums/v408/gotm4/faaaf2fe.jpg
http://img.photobucket.com/albums/v408/gotm4/a275f4b1.jpg
http://img.photobucket.com/albums/v408/gotm4/31b71894.jpg
http://img.photobucket.com/albums/v408/gotm4/837eb1d1.jpg
Nice work Robb!
makes me wonder why the "ears" on the GB in the first place...
Nice work Robb!
makes me wonder why the "ears" on the GB in the first place...
Probably easier to machine.
The original gas blocks are investment cast... so I'm still left wondering their intended purpose.
Robb Jensen
05-17-12, 22:28
The original gas blocks are investment cast... so I'm still left wondering their intended purpose.
Might be for when the rifles are assembled. The ears and where the set screws gives a nice flat surface. It might be used with a alignment tool to make sure that the gas block is mounted in perfect alignment with the barrel and centered over the gas port in the barrel. They are nice gas blocks and made out of 17-4 stainless steel.
Is there anyone here on M4C that professionally installs URX rails AND pin/welds muzzle devices and is looking for business?
I figure that much, yeah. Although with no FSP grind it would be even less.
Good to know, though! I've been wanting a URXIII for a while now but I want a cerakote job one it. It would be a strange task.
It can be done...
http://img.photobucket.com/albums/v340/roguedemon/IMG_0980.jpg
http://img.photobucket.com/albums/v340/roguedemon/IMG_0975.jpg
Dude, you pretty much have my dream build. Few minor differences but wow! You obviously have really good taste. Thanks for sharing. :D
I'm thinking about changing a couple of furniture related things, and still mulling over optics.
Probably going to be topped with a VX-6 or a Mark 6.
This is the place that did my Cerakote... http://www.larsontactical.com/
I sent them all the stripped parts and they did the rest. Joe is a good guy there, very quick turn a round.
Did he put it all together?
No, I did. I bought the barrel nut wrench when they dropped in price.
No, I did. I bought the barrel nut wrench when they dropped in price.
God i hate you. I've been looking for a barrel nut wrench for the past month and a half. :suicide: :sarcastic:
I had good luck finding one by googling the part number and "barrel nut wrench".
They pop up from time to time.
This picture is a better reflection of what the finish looks like, the blue-ish LED camera flash plays tricks with the picture.
Taken outside in sunlight;
http://img.photobucket.com/albums/v340/roguedemon/photo1.jpg
I had good luck finding one by googling the part number and "barrel nut wrench".
They pop up from time to time.
This picture is a better reflection of what the finish looks like, the blue-ish LED camera flash plays tricks with the picture.
Taken outside in sunlight;
http://img.photobucket.com/albums/v340/roguedemon/photo1.jpg
LoL i did that already and went to about 20 different online retailers. They're all out of stock. Unfortunately though, i only did that within the past week or so. A month ago when i first started looking for one, i only went to a couple of sites that i knew sold the thing :sad:
I had good luck finding one by googling the part number and "barrel nut wrench".
They pop up from time to time.
This picture is a better reflection of what the finish looks like, the blue-ish LED camera flash plays tricks with the picture.
Taken outside in sunlight;
http://img.photobucket.com/albums/v340/roguedemon/photo1.jpg
What did you use to keep the rail aligned to the upper receiver?
I have a wrench and I'm still debating if I want to mail my upper off to someone who's a professional to get it swapped out as I'm worried the rail will twist when I re-tighten the barrel nut.
I have a PRI rail receiver block, which fits very snug to the upper/rail. I lined stuff with some blue painters tape to keep everything from marring. Don't know if it was necessary, but I figured it couldn't hurt.
Also, I installed the rail onto the upper with blue loctite, then let it sit for a few days and dry so there was less of a chance of anything twisting as the loctite was dry holding the rail to the upper.
Thanks for the tips, I hadn't thought about doing it in stages.
EzGoingKev
09-29-12, 09:04
One thing I would suggest when loctiting the rail to the upper is install the barrel and put some torque on the nut. Once the loctite has set up disassemble and re-assemble for real.
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