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Discussion Starter #1
Looking for Advice: Stripping this MR 556 A1 Competition rifle completely down has admittedly proven to be a PITA, though I'm not at all surprised by this outcome. Anyway - I'm down to the final pieces...removing the barrel itself, and removing the little screw-in guide thing that captures the piston rod when inserted into the upper.

First, the barrel. This thing is in the receiver TIGHT...like pressed in tight. I have and used the HK barrel nut tool, but getting the barrel extension out of the upper receiver is the real issue here. I've got a Brownell's AR upper receiver vise block that pretty much works - but even with the MR upper secured in my vise, I was unable to get the barrel to separate from the upper. I've heard that HK might freeze/cool the barrel and heat the upper receiver during factory assembly of the rifle...if this is the case, and the specs are that tight, I'm not sure where I go from here. Any advice on removing the barrel from the upper would be very welcomed. I'd also welcome particular information needed to be successful at reinstalling the barrel.

Second is the screw-in guide for the piston assembly. I haven't messed with this yet. This thing obviously screws in, so I imagine I'll just need to find something that fits into the tiny slots at the front face. Hopefully it's threaded lefty-loose. Anyway, again, any advice would be most appreciated. I'd like to be able to take this thing apart and put it back together without sending it off, so I really do appreciate all the help.
 

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I don't know about pulling your barrel out? I can say that on the two stripped 416 uppers I have, I was able to use a screw driver to get one of the piston rod guides out, and on the other I have played hell to get it out. I kinda think the second one is locktited in or something. Also on my stripped uppers, I'm able to slide the barrels into them, they go in tight, but I don't have to use any tools.

I know there are several members on here who have pulled factory barrels, and some have mentioned it is difficult, but I do not know how they have done it.

good luck
 

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My barrel was snug, but it came out without drama. I'd use a rubber hammer and tap forward on the back of the gas block, or backwards on the front of the upper receiver (taking due care to avoid damage, of course). I never tried to remove the piston guide.
 

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Discussion Starter #4
Have an update and still need advice from those in the know...I got the MR556 barrel out. It wasn't easy, and unfortunately required some hammering, but it's out - and appears to be undamaged. I still need some advice on the piston guide that screws into the upper. Is there anything I should know when trying to remove this thing? Does it screw in clockwise or counter-clockwise? Is there an armorers tool for installing and removing it from the upper? Again, any help/advice would be most appreciated. Thanks.
 

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I have done several and have had next difficulties there's a couple people that have done dozens maybe hundreds.. Ask James (Marine0303)
 

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Like I said, on the two I'm stripping down for re-finishing; one came out easy, the other I'm pretty sure is locktited in or something. Heat is a good idea.
 

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Discussion Starter #11
Finally got the damned piston rod guide out this evening. It was loctited in - so it took an easy-out to remove it. Lucky for me, a replacement isn't hard to find.
 
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