Magpul CTR on RRA

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Posted: 8/31/2010 3:17:19 PM EDT

Does anyone have any experience with a commercial CTR on a RRA receiver extension? My dad got a CTR last week and it fits VERY loosely despite having the friction lock engaged. The friction lock tightens the play up a little but it still fits as loosely as the pos factory stock. Is the RRA tube smaller than standard or did he get a defective stock? Can the stock be modified in any way to reduce the wobble? Thanks for the help.

Posted: 8/31/2010 3:21:13 PM EDT

[#1]

YMMV with any stock / tube combo. You can wrap some electrical tape around the receiver extension until the wobble is gone from the stock.

ETA: RRA uses a commercial receiver extension (check to see if thats what he got). My milspec moe is tight, tight on a recent build ( DSA extension.)

Posted: 8/31/2010 3:36:05 PM EDT

[#2]

Are you SURE it's a commercial receiver extension? If it is, you probably just got one on the small end of the tolerance scale, it's not uncommon for commercial REs to have a wider range of diameter variance, from what I hear. Doubtful it's the stock, but if you don't have another rifle to try it on it will be hard to tell.

Posted: 8/31/2010 3:58:07 PM EDT

[#3]

I assume it as a commercial tube. The end is slanted. That means it is commercial, right? Maybe we can modify the friction lock somehow.

Posted: 8/31/2010 4:09:19 PM EDT

[#4]

You shouldn't have any play. All my CTRs lock up tight. I've never had to fiddle with them. I don't have any commercial stocks/tubes though.

Posted: 8/31/2010 4:22:32 PM EDT

[#5]

The OEM commercial RRA receiver extension has been known for some time to be a loose fit with the CTR.

I've read several threads like this one, some even where Justin from Magpul chimes in, and the consensus is always that it is the RRA tube.

You could replace your tube with a DPMS or other commercial tube to go with the stock you bought, or return it and buy all mil-spec size parts (tube and stock body).

Posted: 8/31/2010 4:28:48 PM EDT

[#6]

I, briefly, had a Commercial ACS and commercial tube and there was a lot of play. The friction lock helped but only brought it down to the factory stock, exactly as you report.
I sent them back (it was an order mix up, I had ordered milspec) and once the milspec ones arrived it was rock solid. From what i remember the tolerances are not as tight in commercial spec as milspec.

Posted: 8/31/2010 4:29:13 PM EDT

[#7]

RRA uses commercial "spec" tubes. There are a wider range of variances with commercial tubes than there are with milspec tubes, although having a milspec tube will not guarantee a tight fit. With a milspec tube, you have a better chance at getting a tight fit though.

If you're gonna get a CTR, I'd say go ahead and get a new tube too. If you don't want to do that, I tighten up the CTR on a carbine using a feeler gauge blade. I just cut it in half and epoxied half of it in the front and the other half in the back in the flat channel of the stock. Really tight now.

Posted: 9/1/2010 1:47:39 AM EDT

[#8]

good idea Tony. We might give that a try. My understanding is that RRA puts the tubes on with an unbelievable amount of thread locker. Dont think dad wants to put a torch on his new baby!!

Posted: 9/1/2010 3:24:51 AM EDT

[#9]

I had the same issue with my commercial spec tube on my bushie...it would lock up but would still allow some movement.

Posted: 9/1/2010 5:50:01 AM EDT

[#10]

I have a CTR on my RRA. As stated the com. tube will have an angled cut. It has been on both of my RRA and has the same acceptable play movement on both of them which is not enough to elec. tape it and I'm anal about rattle and slop.

Posted: 9/1/2010 9:08:25 AM EDT

[#11]

Well...at least I'm not the only one. I too have a RRA with the commercial extension. I bought the commercial CTR for nothing more than to stop the rattle trap that it had on it. After installing it....I was a little pissed. Yes, it did lower the amount of slop, but nothing like it is on a MIL spec extension with the MIL CTR on it. I was hopeing for that "no-slop, solid as a tank" feel. I may try the electricial tape trick. I'm sure the reason is the dimensions of the commercial set-up, and not the CTR stock body.

Posted: 9/1/2010 11:51:21 AM EDT

[#12]

Quoted:
good idea Tony. We might give that a try. My understanding is that RRA puts the tubes on with an unbelievable amount of thread locker. Dont think dad wants to put a torch on his new baby!!

I bought a commercial CTR for my complete RRA lower, and it was very loose. The only way to go is a complete milspec kit. From my understanding commercial aftermarket stocks are built to a 1 size fits all spec. For what its worth a Co-worker and I broke my castle nut loose with a stock wrench and our bare hands. No torch or vice needed.

Posted: 9/5/2010 10:41:26 AM EDT

[#13]

I have a commercial CTR on an RRA extension. Mine's fairly solid. There should not be a lot of looseness there (there will almost always be a little). Maybe it's out of spec.

Posted: 9/5/2010 11:27:23 AM EDT

[#14]

Quoted:
The OEM commercial RRA receiver extension has been known for some time to be a loose fit with the CTR.
I've read several threads like this one, some even where Justin from Magpul chimes in, and the consensus is always that it is the RRA tube.
You could replace your tube with a DPMS or other commercial tube to go with the stock you bought, or return it and buy all mil-spec size parts (tube and stock body).

Posted: 9/5/2010 11:44:25 AM EDT

[#15]

I have two CTRs on my RRA lowers and there is zero wiggle. It is locked up very tight. It is just as tight as the CTRs on my milspec tubes, so I am not sure why yours is loose.

Posted: 9/6/2010 6:01:24 PM EDT

[#16]

I have one on my RRA. However, I used a receiver extension from ATI on my lower and it has just a slight amount of play in it. Far from what I'd call sloppy and not enough to be a problem. Exactly what are you guys doing with electrical tape? Can you post a pic?

Thanks, Gary

Posted: 9/6/2010 6:06:36 PM EDT

[#17]

Quoted:

I have two CTRs on my RRA lowers and there is zero wiggle. It is locked up very tight. It is just as tight as the CTRs on my milspec tubes, so I am not sure why yours is loose.

Although RRA always used a comm-spec tube, there was a change in supplier at some point and that is when the complaints about fitment with the CTR started.

Older RRA comm-spec tubes fit better than the current one. Nobody can tell you when this change occurred, but I bet the folks that say theirs fit fine have older production examples.

Also, RRA now offers a mil-spec receiver extension as an option when specifying a custom build, and I think they get you for an extra $25 or if that's what you select.

Posted: 9/7/2010 6:51:12 AM EDT

[#18]

http://www.ar15.com/forums/topic.html?b=2&f=124&t=194131

This was asked in the Magpul forum and replied to by Justin-Beard of Magpul

Quoted:
RRA factory tubes are commercial diameter.

reply by Justin-Beard
Correct, BUT we have discovered that newer RRA commercial-spec receiver extensions are unfortunately too narrow in the width of their lower rail. The newer ones measure to about 0.465” wide which is about ten to twenty thousandths out of range. However, older RRA tubes (I have some samples from mid 2008) measure around 0.485” and fit great with our stocks. Please see these specs for reference.

Since this is the area the CTR Friction Lock makes contact with, and since rotational movement is determined by the width of the rail, it seems as if newer RRA tubes are just too small in that area for a good tight fit with our stock. At this time your best course of action would be to install a commercial-spec tube from a different manufacturer.

[ARCHIVED THREAD] - Magpul CTR on RRA

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