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Posted: 2/13/2009 1:14:47 PM EDT
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I just completed my lower build (registered SBR) and none of my uppers will fit.
the upper is just so tight it will not close. what to do? ETA the lower is a RRA. marked 9mm the uppers are Colt 5.56, CMMG 5.56 and RRA 9mm (just for comparison) as I understand it all lowers are the same wether 9mm or 5.56 right? |
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Quoted:
could u be more specific? how are they tight? the pins not going into the holes, or the halves cannot connect at all? ok, 1) the front pin is very tight, would need to be hammered in to close. 2) when the front pin is in most of the way (not hammered in) the two halves will not close. there is at LEAST 1/8 to almost 1/4" between the two halves. also when rotating the two halves there is significant resistance or pressure at the front piviot area. I can see where there is a contact point at the rear of the receiver where the upper touches (near the buffer tube opening) this is a brand new lower. |
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Quoted:
I had a problem with an RRA lower before,,,when I attached the upper to the front pivot pin I couldn't get it closed completely at the rear, Had to send the lower back to RRA for replacement. unfortunatly i can't really replace this lower, it's registered SBR. 
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This is a well documented "problem" with RRA. I personally see it as a benefit. Add a little CLP to the rear lug, and work the upper onto the lower. You will break in the lower, and when the upper can fit, you'll have a upper/lower mating that's rock solid. Most other ARs are slightly wobbly between the upper and lower. If you swap out uppers too much, eventually your RRA will be as loose as other brand lowers. |
| Wow, I was going to say it is supposed to be tight... but not that tight! I know you said the front pivot pin is tight, but is it hanging up anywhere else? Do you have any other working lowers you can compare it to? You may have to take it up with RRA, a damn shame on your SBR! |
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So before you sent out the 200 bucks to the ATF you didn't bother to try the lower with any uppers for fit?
Did you buy this as a factory SBR from RRA? If it is factory then send it to RRA for repair but if its made a SBR by you I think you should have tried it first. |
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While I can not tell you whats wrong with yours.... This was the issue with mine. Same thing to tight. What I did was evaluated where it was to tight. What the deal was the CORNERS was hitting. They ( RRA ) didn't mill the lower quite deep enough. So the upper pin block corners was dragging during the closeing of the rifle. All I did was take a smooth file and lightly broke the corners . The two REAR corners that was making contact. It took 10 seconds to do. That's all it was. I'm sure that's probably whats wrong with yours. You will damage your upper pin block in no way at all doing this. Your filing the UPPER not your LOWER SPR ... Check it out and get back to us....... WarDawg
P.S. Put your front pin in first and trying closeing the two ( upper and lower up. You can tell quickly the issue at hand. ( NOTE ) I did NOT file the side walls of the pin block only the two rear most corners to give it a 45 degree angle to give it a little clearance... .... It's r4eally a non issue if it turns out to be this....... WarDawg |
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Quoted:
While I can not tell you whats wrong with yours.... This was the issue with mine. Same thing to tight. What I did was evaluated where it was to tight. What the deal was the CORNERS was hitting. They ( RRA ) didn't mill the lower quite deep enough. So the upper pin block corners was dragging during the closeing of the rifle. All I did was take a smooth file and lightly broke the corners . The two REAR corners that was making contact. It took 10 seconds to do. That's all it was. I'm sure that's probably whats wrong with yours. You will damage your upper pin block in no way at all doing this. Your filing the UPPER not your LOWER SPR ... Check it out and get back to us....... WarDawg P.S. Put your front pin in first and trying closeing the two ( upper and lower up. You can tell quickly the issue at hand. ( NOTE ) I did NOT file the side walls of the pin block only the two rear most corners to give it a 45 degree angle to give it a little clearance... .... It's r4eally a non issue if it turns out to be this....... WarDawg Then use Aluminum black to coat and touch up those filed areas. Will turn black on contact. Should have checked before you SBR'ed it man. Best thing to do is call RRA and see what they can do for you. |
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well, I examined closely what was hitting, it appeared that it was just "new" tight.
so I took a chance and just strongly closed it a few times. not slamed it, but more than just closeing it. seemed to work. the pins are still tight but everything lines up propperly I did a funtion test and all seems fine. I'll go shoot it this weekend if the weather cooperates. whew. 
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