ar15 upper issues

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pow

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I am having two issues putting an upper together, since this is my first build I'm not sure on a couple of things. The first issue is getting the forward assist to run smoothly. When I have a punch stuck through, it operates properly. As soon as the roll pin is about half in, it seems to bind up. I read a spiral roll pin would solve this. Thoughts? Additionally, I am having issues getting the gas block to slide on. I have read you can freeze the barrel and heat the gas block and it *should* slide in to place. This seems kind of permanent to me. Any ideas?
 

clock152

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for the forward assist... I find it helps to push it in a bit while driving the pin in (BTW.. I use a pair of Chanel locks with tape on one jaw to keep from marring the receiver to press the pin in instead of driving it.)
What type of gas block are you using? Do you have correct size for your barrel?
 

NightShade

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I'm not far away, if you want I can come take a look and see what is going on or you can head this way but sounds like there could be something wrong with the roll pin or the forward assist could be rotating when you are driving the pin in. As far as the gas block if it just barely will not fit or is catching look and see if there is a bur inside the block or on the outside of the barrel that needs to be knocked off. As far as the heat cool method it can work but if it's an aluminium block I wouldn't want to go heating it up all that much to make it fit. May be easier to just hit one or the other with a little sand paper as either the barrel or block could be slightly out of tolerance or maybe both, it the barrel is big and the block is slightly small it can make a huge difference. Sometimes the coatings that are applied can get a little thick too and if the tolerance is really tight that could cause a problem.

Otherwise you may be able to head over to Safety First in the old Heartland outdoors building and see if one of those guys see anything acting up with it.
 

pow

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I appreciate the information. At this point, I feel it is definitely an issue with the gas block. It appears that all of its holes are out of specification, gas tube and roll pin are both too small.
 

dlbleak

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sometimes they can be a real PITA to get the roll pin in or even started. i have a few roll pins if you want to try another one. can't help with the gas tube hole though. what brand is the block? if its a known maker, i'd get a call into them.
 

Shootin 4 Fun

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Your forward assist may be rotating as you install the pin. Once you get the roll pin in far enough to keep the f/a from popping out take a look and make sure that it's straight.

Gas block, a lot of manufacturers have tightened up their tolerances and those things can be a cast iron ***** to install. You may have to sand some of the finish off of the inside of the block.
 

pow

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It's a Troy gas block. I was able to get the gas block to slip on. Against my better judgement I heated it up and slid it on. I had to get pretty rough with it to get it back off, I guess it is possible I somehow deformed the gas tube opening. I'm still kinda puzzled about the roll pin hole though. I should have an assortment of roll pins tomorrow.

Thanks for the help and ideas.
 

pow

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So I was able to get a new/beefier roll pin for the forward assist. This has smoothed the forward assist way up.

Thanks again.
 

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