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Posted: 6/21/2003 10:33:33 AM EDT
[Last Edit: 8/4/2003 2:35:57 PM EDT by Minuteman419]
I was just installing a RRA FF tube on a New RRA upper and New RRA Heavy barrel (1x12). While I was tightening it to get the gas tube holes aligned between the tube and upper, I thought the barrel turned in the barrel vise (it didn't). I know that some of you don't recommend using them and prefer the receiver block thingey. I then noticed the gas port in the barrel was out of line somewhat and is not gonna line up with gas block. Am I correct in assuming that the barrel extension backed off somewhat from the barrel. The alignment pin for the upper and the upper are ok.

Sould I order an extension wrench and tighten it back myself or send it to someone to have this done? I have been comfortable for years as a DIY'er. What is cost of wrench vs. having someone do this?

Where can I either order tool from, or send whole barreled upper to and have it back reasonably quick and done right?

Your thoughts are appreciated.

MM419
Link Posted: 6/22/2003 12:08:16 AM EDT
It is unlikely that the barrel extension has come undone as it is torqued to 150lb/ft and pinned !Assuming that the gas port and index pin in the barrel extension were aligned correctly before fitting the barrel into the receiver,I would remove the FF tube in order to check that the whole assembly has not twisted out of line.
Link Posted: 6/22/2003 5:40:19 AM EDT
Thanks FAHR451, I'll remove it again this afternoon and check it again. I was replacing the Hogue tube with the RRA when all this took place. The Barrel and gas port were fine before I tightened the RRA FF Tube the last time. The rifle shot and functioned fine. Now it is a jam-a-matic. MM419
Link Posted: 6/23/2003 12:25:05 PM EDT
[Last Edit: 6/23/2003 3:05:57 PM EDT by Minuteman419]
Ok, the barrel is off the receiver again, sighting down from alignment pin to gas hole, it is out of line, not a great deal. Pin is ok and slot in upper is fine. I need advise, please on what to do. Does the pin go down through the chamber extension and into the barrel threads? Could the pin be sheared off under there? Pin will not pull out of extension either. I looked at other threads on the site and cannot still come up with an answer to my original question about just tightening it back. Someone please help, I'm running out of hair to pull out and this is to be my varmit rig. TIA MM419
Link Posted: 6/24/2003 7:55:04 AM EDT
It is highly unlikely for the pin to have sheared, or the extension rotated on tightening of the barrel nut, as the extension is torqued to 150lb/ft. The index pin is of mild steel which should not sheer at barrel nut torque i.e 30lb/ft-80lb/ft absolute max(in order to line up the next slot for the gas tube) as you say there is no damage to the receiver to suggest this.The gas port should line up EXACTLY with the index pin as this is drilled on exactly the same plane.It is essential that it does this to ensure that the front sight post/gas block aligns with the port without covering any portion of it.If it looks out by eye then it is probably a long way out!The pin does go into the barrel threads around 0.010" which leaves sufficient material proud of the extension to locate into the receiver slot without intefering with the threaded portion.(the pin is 0.180" long, give or take a couple of thou) It would appear that this may be a quality control problem at RRA(Even the best have off days).I would suggest a call to them to discuss the next move.
Link Posted: 6/24/2003 1:03:05 PM EDT
Thanks FAHR451, I'm going to make the call now. This has been a learning experience for me. As many barrels as I have swapped out, this one turns out to be a PITA. I'll post what happens later. MM419
Link Posted: 6/24/2003 11:59:58 PM EDT
There is a remote possiblity that the barrel extension was not properly torqued before being pinned at the RRA factory.If this is the case on sighting from the chamber end the index pin/extension would have rotated to the right of the gas port,if as you suggested earlier,you thought "something moved".Either way, not your problem !
Link Posted: 6/25/2003 12:40:52 PM EDT
Thanks again FAHR451, I just got off the phone with a Gentleman from RRA. He said to send the barrel and receiver back to them and they would look at it and try to salvage it. I hope you are correct about it not being my problem. I hope I don't have to eat a $200 barrel for something like this. As many of these things that I have done, sooner or later it had to happen. BTW I have an action block now. MM419
Link Posted: 6/26/2003 3:12:32 AM EDT
Link Posted: 6/26/2003 8:54:23 AM EDT
Take as many photos as you can of each of the components,from as many angles as you can,paying particular attention to the barrel/upper receiver mating areas,before sending anything to any one.This coupled with what has already been posted here will ensure that you have recorded the matter as thoroughly as possible, so that you will be treated correctly on reappraisal by RRA. RRA are a very reputable firm and will deal with you fairly and honestly. K is correct when he states that the gas port in the gas block is oversized to accommodate some misalignment.The gas block/front sight post port is normally around 0.125"-0.158" as opposed to the barrel ports 0.070"-0.095",(depending on type),but you said you "thought the barrel turned in the vise" and "then noticed the gas port was out of line somewhat". It was this description and the fact that the misalignment was that noticeable by eye that drew me to those conclusions. As the gas port is drilled,(or EDM'd- some use this technique to dispense with the bore lapping to remove possible burrs), AFTER the index pin is installed ,(hence the reason for the number of barrels for sale profiled, B.E.'d and headspaced but WITHOUT gas ports drilled, available in the AR15 Parts section of this hallowed Site),then there is no real reason to have the port out of line any more than a couple of thou as the milling head should be indexed off the barrel extension pin centre before drilling the gas port.The mill table is just then traversed the corect distance to suit the application(whether CAR,Midlength of Rifle) and the port centre marked and then drilled. This process can be done accurately with a standard drill press and using a jig and v-blocks, as I have described in another thread. It would be extremely difficult to detect BY EYE, a gas port that has been formed a couple of thou off the barrel centreline. It is true that "out of line" witness marks are left by front sight posts and gas blocks,but this is should be due to the fact that the front sight posts are aligned with the rear sight aperture at its theoretical (assumed) centre, and the gas block(without a sighting device)and tube is arranged with the carrier key bore and hole in the upper receiver,with all the accummulative errors these methods of installation can produce,and not because the gas port is out of line with the index pin.
Link Posted: 6/27/2003 4:36:16 PM EDT
Thanks Guys! The barrel, upper, ff tube went out Priority to RRA yesterday afternoon. The ball is in their court now. MM419
Link Posted: 8/4/2003 2:39:17 PM EDT
Hello all. Just got the upper back today and put several rounds downrange with no problems at all. RRA did fine by me, cost me a whole $45 to cover labor and shipping. I'm satisfied. Now to work up some loads for the whistlepigs. Thanks to all who offered advice! MM419
Link Posted: 8/4/2003 3:43:38 PM EDT
What was wrong? What did they do to correct it?
Link Posted: 8/4/2003 4:25:27 PM EDT
Originally Posted By bgenlvtex: What was wrong? What did they do to correct it?
View Quote
Hello, it's easier for me to refer you to the top post in this thread than type it over again. (can't type fast) Long story short, the barrel extension backed off while I was tightening the FF tube onto the upper while trying to align the gas tube and holes. These were parts I got new and assembled myself (not my first job doing this by any means). They apparently fixed the problem by retorquing the barrel extension and re-aligning the gas port. I sent them parts and got the upper back assembled. And, it functions fine now. I have since got a receiver block from Brownells and will be retiring the barrel blocks, only using them for replacing flash hiders and the likes. Regards... MM419
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