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Posted: 10/9/2004 1:49:13 PM EDT
Just got back from the gun show here in Tampa, and bought a complete RRA lower(with the new markings), and had the dealer install the ACE M4 SOCOM stock. I brought it home, and put the upper I had in mind for it on the lower. It doesn't seem to want to fit, and I need a little help please.

The upper I am using fits all of my Colt lowers fine, first of all. The upper is one that was put together. The barrel doesn't matter, but it is a Colt 14.5" M4 with a permanently attached Phantom. The upper receiver was one that a local gun dealer had, and I am not sure if it is a Colt. Since this was to be my "shooter" I wasn't too concerned with it. It is an A2 upper. When I tried to put it on this RRA lower, the rear of the upper doesn't seem to want to go fully into the rear of the lower. I figured that maybe the RRA has some tight tolerances, so I tried several times but did not want to(and shouldn't have to) beat the upper onto the lower. The rear pin is SO close to going into the upper, but there seems to be a slight gap between the upper and lower in the rear, and I cannot get this thing on.

Is it possible that my unidentified upper receiver may not be "right" for the RRA lower? I test fitted this upper onto my other Colt lowers, and it fits them all. I can also get my other uppers to fit the RRA lower. Anyone ever run into this, and possibly give me some feedback? I really don't need another excuse to buy another upper right now....

Thanks in advance!
Link Posted: 10/9/2004 2:04:26 PM EDT
Link Posted: 10/9/2004 2:07:44 PM EDT
Hey, I was there after the car show.

Anyway, the RRA lowers are very tight. People on AR15.com say, you have to smack the upper into the lower for the first few times. After the first time, you will see where the upper is rubbing. Just put it together a few times and you'll be shooting soon.


Link Posted: 10/9/2004 3:12:16 PM EDT
check out RB Precision's website..a specific method for RRA lowers/uppers assembly is listed there..Robert is one of the experts on RRAs
Link Posted: 10/9/2004 9:45:48 PM EDT
Link Posted: 10/9/2004 11:23:10 PM EDT
I had the same thing when I first assembled my RRA lower. as everyone has already said it is normal or least expected. Lightly tap the upper on and after a few opening and closings it'll be the best fitting upper/lower combo you own.

Link Posted: 10/9/2004 11:31:43 PM EDT
My RRA lower was as tight as hell. I used Dremel a bit and now it's perfect.
Link Posted: 10/9/2004 11:56:20 PM EDT
[Last Edit: 10/9/2004 11:56:43 PM EDT by dragunov]
Link Posted: 10/10/2004 12:14:29 AM EDT
I had the same situation with two of my RRA setups. Just smack it down into there and put a couple hundred rounds through it. Then open and close it a few times, it will be right as rain.

As for the rear pin, you might have to gently use a rubber mallet to tap it in the first time.
Link Posted: 10/10/2004 3:14:32 AM EDT
I had the same problem with a Bushmaster upper receiver. My solution was to buy a RRA upper receiver and sell the Bushmaster. No worries after that!
Link Posted: 10/10/2004 4:21:08 AM EDT
Iron Oxide = rust
Aluminum Oxide = rust


Link Posted: 10/10/2004 6:06:11 AM EDT
I just assembled my new RRA US Property lower to my SPR clone upper (built on an RRA). The fit and finish are impeccable. Best fit of two products made at different times I have ever had. No "accuwedge" needed as this is simply NO PLAY whatsoever, yet the pieces fit together as tight as the tolerances on a Swiss watch. I'm impressed by RRA. (Disclaimer: no connection to RRA, just a critic who will let you know when things suck, but also praise good products. For example, I've found about all First Samco products I've used to be cheap, flimsy and poorly designed and manufactured compared to about everything they compete with).
Link Posted: 10/10/2004 7:21:53 AM EDT
Thanks for the information, guys.

I'll play around with this thing later today. I do wonder, however, why the Colt uppers go right onto the RRA lower and this one "unknown" upper does not.

Link Posted: 10/10/2004 8:30:45 AM EDT

Originally Posted By 9divdoc:
Iron Oxide = rust
Aluminum Oxide = rust



And, yes, if he leaves that upper, w/the bare spots on the takedown lug, outside for six months, it'll have a coating of aluminum oxide on the bare spots.

Do you really think it's a problem on an inside piece of a rifle, that bears against another piece, and is regularly moved up and down against the sidewall? If so, then all of us who have opened up the actions of our ARs regularly have a problem.

Don't know about anyone else here, but every AR I own has finish wear on the takedown lugs, front and rear.
Link Posted: 10/10/2004 5:07:08 PM EDT
Link Posted: 10/10/2004 7:35:23 PM EDT
Back when dinosaurs roamed the earth I was in RVN with the Riverines...we operated in salt water marshes..brackish water..mud...more mud...deeper mud...and really crummy water buffalo crap mud..
and human fertilzed rice paddies...that plus acrid sweat..did a number on a few older ARs

PM is the key

Link Posted: 10/11/2004 1:39:20 PM EDT
Thanks for the help, everyone. Last night, I sat in front of the TV and worked the upper into the lower for awhile. I lubricated the rear lug on the upper with CLP, and it didn't take long for it to seat properly. Now, I HAVE to go shooting it seems so that I can work the receivers together because the pin is very tight now. Maybe we'll try to go do that this weekend!

Thanks again.... This RRA seems rock solid, and there is obviously ZERO movement between the upper and lower.
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