NickWhite 7 Posted February 3, 2012 Report Share Posted February 3, 2012 (edited) I know people have done it, but what do I have to file down to make it fit? It seems to be hitting the face of the gas tube. I'm thinking something is making the ass end kick up, any ideas to make this work?! Edited February 3, 2012 by Nick9130White Quote Link to post Share on other sites
NickWhite 7 Posted February 3, 2012 Author Report Share Posted February 3, 2012 ON* on S223*** Quote Link to post Share on other sites
mancat 2,368 Posted February 3, 2012 Report Share Posted February 3, 2012 (edited) You need to file the sloped surface of the tube where the release lever engages, but... Make sure to press the '74 tube down and in towards the rear sight block, as it needs a bit more effort to seat it there due to the tension spring and little retaining tang that is down near the bottom - this tang tends to get caught and prevents the tube from fully seating without some manipulation. You want to get the tube down as low as it will go, because even an extra millimeter of height of the sloped surface at the release lever will require you to file off some material there. File too much, and it can become loose. Some people file the front of the tube where it meets the gas block. This doesn't work all that well with the '74 tube, because it has limited movement front to back due to the tang and spring at the rear of it. Edited February 3, 2012 by mancat Quote Link to post Share on other sites
rjwillow 5 Posted February 6, 2012 Report Share Posted February 6, 2012 Hi, Nick... Yup... don't file the front of the tube at all. FUBAR'ed my first one like that... Look at the original tube and note the angles milled into them. If you have a new Polish or Bulgy tube , it will most likely be dead flat on the receiver end. You will need to match those angles and fit accordingly. Once you start roughing it in, hit the mating surfaced with dykem blue or even black sharpie... you will see scrub marks and know where to take off. A few passes with a fine mill file at a time.. One thing to keep and eye on is the right side shoulder of the tube... see if it rubs on the retainer lever. I put my retainer lever in the "open" position and filed the edge that stuck out past the rear sight block flush. I probably should have done that first. But I didn't see the interference until later in the fitting. The relief cut on the bottom is not as critaical and can be rounded a little. But the top cut must match the angle for the retainer lever block. Get it close as you can while it's still tight and put it on and off a bunch of times. Then polish out the file marks and check the fit again. If it's still tight but manageable, leave it alone and shoot it. It will probably wear in a bit and you can always take a few passes with a file or a little more polishing the next time you clean it. Have fun, rich Quote Link to post Share on other sites
MD_Willington 11 Posted February 13, 2012 Report Share Posted February 13, 2012 I have an East German 74 tube on mine (an '06), needed no work at all, just dropped right in. Quote Link to post Share on other sites
jimdigriz 580 Posted February 13, 2012 Report Share Posted February 13, 2012 I know people have done it, but what do I have to file down to make it fit? It seems to be hitting the face of the gas tube. I'm thinking something is making the ass end kick up, any ideas to make this work?! What is hitting the face of the gas tube? Will it seat without your lower handguard retainer in place? If so, you will need to grind away a small bit of material on the bottom of the tube that contacts the retainer. Quote Link to post Share on other sites
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