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Posted: 2/28/2012 9:37:23 PM EDT
| This is my first attempt at a 308 (built MANY AR 15s). I'm having a problem getting my Rainier Select barrel into my monolithic upper. It feels like ethier the barrel is to big or the upper is too small. The barrel will slip and slide about 2/3 the way in, but no more. I have the barrel in the freezer now to so if it will possibly help, but any suggestions? What diameter should the barrel be? I'm going to call Mega tomorrow, but if any one has a suggestion PLEASE chime in. |
| If you have a heat gun or even a decent hair dryer, use it to heat the area of the receiver that the barrel slides into, and that should help get it the last 1/3 of the way. Make sure you fit it all the way in or get it out before the temperature stabilizes or the barrel will not come out easily. |
| A heat gun will get it too hot to touch pretty quickly in my experience. That's how I installed the barrel on my 20" 5.56 rifle, but that thing is never coming out short of cutting up the receiver. The tight fit feels like there is a huge difference in size between the barrel extension and receiver, but the reality is that there is probably less than .001" difference so the amount of expansion or contraction you need is really pretty minimal. As far as the best lube for assembly, I know that Aeroshell is the "mil-spec" grease, but its hard to find in single build quantities and I've never used it myself. I use something called "Engine Assembly Lube" that comes in a black tube for a couple bucks at auto parts stores, but some people don't like it because it contains teflon. Check in the build it yourself forum or trouble shooting forum and there is probably a better answer. |
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I'm glad you got it all worked out. I went through this exact same problem when I built a MEGA MA-TEN using a Noveske barre. That barrel would NOT go in there without force.
I put the barrel in my deep freeze, I used a hair drier and used lithium grease. None of the above helped at all. I finally just lubed it up well, inserted the barrel as well as I could, I slid the barrel nut over the barrel, started threading it in and began tightening the barrel nut. The barrel nut sucked the barrel perfectly into place. I then used a torque wrench to ensure that the nut was properly tightened. That method went slicker than snot! Too easy! |
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Quoted:
Pics or it never happened! glad to hear it worked out. Should he have taken a picture of his fridge? 
Yea, I had the same problem with my Mega Monolithic Upper (5.56) and Noveske Barrel. I actually justed tappped mine with a mallet. I did have to put my roll pin in the freezer to get in in my Noveske Switchblock. |
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Quoted:
Should he have taken a picture of his fridge?
That depends entirely on how much and what type of beer is in the fridge and if he's also going to post his address 
Sounds like the hot/cold treatment worked though and I don't think I've ever seen one of those monolithic uppers fully assembled. |
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Quoted:
I'm glad you got it all worked out. I went through this exact same problem when I built a MEGA MA-TEN using a Noveske barre. That barrel would NOT go in there without force. I put the barrel in my deep freeze, I used a hair drier and used lithium grease. None of the above helped at all. I finally just lubed it up well, inserted the barrel as well as I could, I slid the barrel nut over the barrel, started threading it in and began tightening the barrel nut. The barrel nut sucked the barrel perfectly into place. I then used a torque wrench to ensure that the nut was properly tightened. That method went slicker than snot! Too easy! If it was a normal upper I would have done that exactly. The problem with the monolith is you are blind. You can not see the key/key way for the barrel and you have no visual of the barrel nut either. If you do catch a thread and your barrel is not in the key way you are going to damage the upper and/or cross thread the nut/upper. The only way to tell the barrel is seated is a window at the bottom of the upper where you can see the barrel flange an the mating surface of the upper. I really wish Mega had included AT LEAST a note about heating up the upper in it's instructions. After starting this thread I found many others who had the same issue. I'm almost done. I need to just install my gas block and flash hider. I'm still waiting for my BCG, but Brownells is expecting this week (please!!!). Pictures to come boys! And again MANY thanks for the help! Robert |
Same issue. Froze the barrel, heated the receiver and greased. Still had to use a plastic mallet on an old FH that I screwed onto the barrel threads. Wasn't easy but it is done. Don't know how I would ever get it apart if needed. Barrel nut went on almost as difficult. ID of nut rubbed the OD of the barrel at the chamber area. Grease the outside of the nut, inside of the nut and outside of barrel in this area for easier install. Finally done after lots of #$%*#$. Happy now.
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