View Full Version : Well, I got my upper in. SUPER tight fit/doesn't fit. Got a question
So I just got my upper in the mail last night. Very excited.
I go to put it on Rock River Lower, and it would not go on. The pivot pin goes in nice and smooth, but when I bring the two halves together, it will not join. I did try and force it, but I couldn't get the take down pin all the way through, then it was a beast getting them apart again. The part on the upper that has the holes for the take down pin hits the lower (hope that makes sense) and does got go in nice and smooth like it should. I pulled out the BCG and the buffer just in case that was the hang up, and it still won't go..
Sooooo, I figure it's just the lower. I try it on my Larue lower (no-go) and a Magpul (:D) lower and still no go. I'll try it on a couple more lowers for the hell of it, but this just ain't right.
I know this company will take care of it. But my question is this: when they test fire a weapon at the factory, do they even mate it to a lower? I don't see how. I'm sure they would have picked up this discrepancy if they did, or if I bought a complete rifle from them..
I have an upper right now that appears to work on every lower I have tried it on, except the one I want it to go on (it's an SBR upper), and the original upper that goes on that lower won't fit on anything else. It's a factory Colt 6933, and while I have no intentions of changing the gun in the long term it was a bit aggrevating to not be able to mount up my new upper. Sometimes it's just a matter of tolerance stacking. And there's no guarantee even if you buy a complete rifle that the parts will work with other parts. Sometimes it's just a bad luck of the draw. But if you bought the upper from a reliable vendor or maker you'll obviously be fine, and your situation is just one more reason to buy from known entities with reputations for good service as well as good products.
What brand of upper is it, where did you get it and are you planning on calling them first thing this morning?
What brand of upper is it, where did you get it and are you planning on calling them first thing this morning?
That's what I would be doing. :)
Ehh call them in the morning I would presume they will make it right. If tey don't PLEASE keep us in the know of who said NO.
I called them. They said that it's built that way on purpose and it would get better with time. He said if I didn't like it, then they'd be happy to loosen it up or whatever they do. It's a VLTOR MUR upper receiver, and he said they're just made that way with the extra paint and anodizing.
I'll try and get it on the lower again I guess and go from there. Just have to bring a hammer and punch to take it apart at the range. Hopefully it'll loosen up. :)
It's a VLTOR MUR upper receiver,
Mine too. :mad:
Mine too. :mad:
So is yours impossible to get on a lower?
eternal24k
10-29-09, 10:46
Mine too. :mad:
I have 4 Vltor uppers, they are picky. 1 gen MUR will only fit with a certain gen POF, and another took out some material in the lower fitting it.
Also, the only time I have ever had to heat an upper (really hot, in oven + frozen barrel) to fit a barrel was in a VIS.
I have taken a break from them between the fitment, and the new gen forged uppers having rough finishes and some with gouges under the anodizing, although i have not gotten a newest gen with the angled deflector.
So is yours impossible to get on a lower?
It won't go on the lower I want it to. I have limited options here though as it's an SBR configured upper and I can't legally even try it on non-SBR lowers. I have one other 6933 to try it on, and a 9mm SBR that I'll try it on as well to be sure.
I tried putting one other non-SBR upper on my troublesome 6933 lower and it had fit issues as well so I'm not entirely sure if it's the MUR or not yet. Kind of annoyed right now at having to dick around with it instead of just dropping it on.
I can't get the pivot pin in at all. Whether I start with it "open", closed, takedown pin in first, nothing. The pivot pin just won't go in.
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I can't get the pivot pin in at all. Whether I start with it "open", closed, takedown pin in first, nothing. The pivot pin just won't go in.
I haven't had the pivot pin problem on the 5 or so lowers I own. But when I went to the dealer I picked it up at (to get the shipping box in case I return), we were talking about it and he wanted to try it on a RRA lower he had. The pivot pin was WAY tight, and we couldn't get it to fit in the rear.
SO, do I return and have them make it so it'll fit a bit better, or do I just force it on the lower and hope it loosens up some? I think I'll force it and shoot it first.:confused:
....... The pivot pin goes in nice and smooth, but when I bring the two halves together, it will not join. I did try and force it, but I couldn't get the take down pin all the way through, then it was a beast getting them apart again.....
I think you will find that all of the VIS and MUR are built to be tight. Tap the pin in the rest of the way, and it will flush up. You will probably have to tap the pin back out with something as well. As you shoot it, it will loosen up.
Think back to when you were in the military. Some of the weapons off the rack were loose, and some were so tight you needed to use an object to push or tap the pins out.
Any reason for not sending the lower to the builder of the upper? One trip and it should be fine, if the builder stands by their word.
MP
Tolerance stacking with RRA components like the OP's lower is a norm, not an exception, and should be expected. Despite marketing to the contrary, their typically tight fits and "better than spec tolerances" aren't usually a good thing.
DialTone301
10-29-09, 13:21
My MUR fits snug but not tight on the two RRA lowers that I have.
Belmont31R
10-29-09, 13:31
Tolerance stacking with RRA components like the OP's lower is a norm, not an exception, and should be expected. Despite marketing to the contrary, their typically tight fits and "better than spec tolerances" aren't usually a good thing.
Ive noticed the majority of people with fitment issues usually have RRA lowers.
Ive noticed the majority of people with fitment issues usually have RRA lowers.
I wish I could retitle DO I HAVE A LEMON?? .. Anyway, it doesn't fit on a Noveske, Larue or Magpul lower either, so it's NOT a lower issue.
I think you will find that all of the VIS and MUR are built to be tight.
Sounds like we might have a discrepancy between "tight" and non-fitting.
Also seems like a discredit that 3 separate posters here mention the same problem in this brief thread.
Sounds like we might have a discrepancy between "tight" and non-fitting.
Also seems like a discredit that 3 separate posters here mention the same problem in this brief thread.
There is certainly a difference between tight and not-fitting. The OP has commented that his take down pin presses part way in, which is how mine are, they are tight, and need to be tapped in the rest of the way.
Rob says his won't go in at all, which is a different issue.
The problem when dealing with internet "issues" is that you don't know what you are really dealing with. A guy who is used to push pins slopping in and out is going to be very unhappy with a MUR or VIS. A guy who is used to hard pressure when pressing pins in or out probably won't be all that excited or upset. I don't say this referring to the OP, I mean it as a general comment when talking about online issues. All to often it becomes a matter of a faulty trigger actuating nut.
Well, gentlemen not to jump on the bandwagon but I have a new gen. MUR that is also extremely tight fitting, as in tapping pins in and out of not only receivers but also my upper rec. block for installing barrels. I know of many people who like super tight tolerances between their upper & lowers. I personally like a little slop!:D
I wish I could retitle DO I HAVE A LEMON?? .. Anyway, it doesn't fit on a Noveske, Larue or Magpul lower either, so it's NOT a lower issue.
I have an LMT MRP and putting it on my lower was always a bitch. Putting it on any lower is a bitch. The pivot pin goes in nice and easy, but there are two tabs on the MRP receiver that hit the lower before the takedown pin hole makes a good fit, so for the first 20 or so tries, I literally had to put all of my weight on the lower, push it in the upper, then the pin went in nice and easy. It's always fired fine, and I can now take the pin in and out with (some) easy.
If that's the same with you, no it's not a lemon. It's just a tight fit, which is somewhat of a good thing depending on the way you look at it, after it gets warn in.
I've had other receivers be tight fits on the pins. My brother and I did a rifle with a DD upper and it was tight on the pins. Really really tight. Some emory cloth on the pins and inside the whole to take away extra anodizing made them nice and smooth.
15 years ago I had the same issue with some BM parts I was using.
A very fine emory cloth to "wear" away some of the finish inside the takedown pin holes in the upper and on the pins usually does the trick
My MUR I have will mate with most uppers but the pins are not installed yet. raw upper
Chad
Get a bigger...
http://www.ajstools.com/products/setting/images/hammer4.jpg
Well I hammered it down and it's together. After lubing it up a bit and manipulating it, was a little rough to pull back the CH.. seemed OK...just OK. Well, I pulled it apart and the charging handle is scratched to shit on one side; the entire length.. No biggie. Put in a gas buster and it's smoother. So I'm going to get it sighted in tomorrow and run a coople hundred through it and see how it goes.
I wish I could retitle DO I HAVE A LEMON?? .. Anyway, it doesn't fit on a Noveske, Larue or Magpul lower either, so it's NOT a lower issue.
Generally speaking, billet on billet usually equals a SUPER tight fit to not working at all. If you have a newer MUR, then it is not billet, but still tends to be on the large side of the spec.
You are welcome to send me your MUR and I will run it across the 300 + lowers we have in the shop and find one that matches for you.
C4
Jay Cunningham
10-30-09, 10:02
I wish I could retitle DO I HAVE A LEMON?? .. Anyway, it doesn't fit on a Noveske, Larue or Magpul lower either, so it's NOT a lower issue.
You can. Just edit your original post under "Go Advanced" and it will let you change your thread title.
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