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Posted: 1/15/2008 3:06:15 PM EDT
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Recently I order a 20” Chrome Moly Barrel from Rock River. After mounting the barrel to my receiver and trying to installing the gas tube, I discovered that the gas tube retainer pin holes did not line up with the holes in the FSB. So, I removed the barrel from the receiver to try and determine if there might be some debris in the gas tube hole in the FSB. No debris was found. After some thought, I decided to file the end off a old gas tube to see how much material would have to be removed from the end of the gas tube in order for the FSB gas tube retainer pin holes to line up with the gas tube retainer pin holes. It turned out that about a 1/8 of an inch had to be filed off the gas tube. Conclusion; the gas tube hole in the FSB was drilled about an 1/8 inch to swallow. Now my new concern was “will the gas tube port line up with the gas port in the FSB. So, I assembled the gas tube and finished installing the barrel. Next problem: the front sight post would not screw down. The front sight base was larger in diameter than the cut out in the FSB. After trying several different front sights it was time to bring out the dermal. Using a sanding drum I removed enough material so the front sight could screw down into the FSB Next problem: the front sight retainer was too big for the hole in the FSB. Again I had to use the dermal. I have built a number of AR’s and have never had a problem like this. Has anyone else had these kind of prblems? |
| "Chemo Brain" after two rounds of Chemo it's a wonder I can spell my name. And no I am not doing something wrong. The FSB was of poor quality control. The gas tube hole wasn’t drilled to the correct length. And the front sight retainer pin hole was too small in diameter. I used a set of micrometers to measure both against and older FSB I have. I am considering changing out the FSB for the older one. But, I think if you buy a new barrel with a FSB you shouldn’t have to do this. That’s the engineer in me. |
have you talked to rock river? Mike |
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