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View Full Version : Ar15 uppers to snug for lower!


dancinzen
10-28-2010, 4:47 PM
Howdy, I just bought two new uppers and both of them are so tight on my lowers I need a punch and hammer to knock the pins out and in to connect and dis connect the uppers and lowers. I know this is good for accuracy, but it really bother me in the sense that if I was ever In a sticky situation or out shooting somewhere with no tools, I would not be able to dissaselble the ars to fix or matinence them. Is there any ways or ideas to lossen up the pins or uppers holes?

xibunkrlilkidsx
10-28-2010, 4:49 PM
..drill them out. seriously do a search there have been tons of these questions lately. shot it and they will loosen up a bit. Mine were like that as well when i got it. now i can use a dummy round and body weight to get it removed. or get your drill out and enlarge the holes if it really bothers you, not a recommended solution.

Merc1138
10-28-2010, 4:54 PM
Drilling the holes wouldn't accomplish anything if it's just the detent for the pin that's the "problem".

Noobert
10-28-2010, 4:57 PM
Yeah, it's not entirely clear what you have that is tight. Take the lower without the upper and tell us how tight the pins are compared to when you have the lower with the upper.

dancinzen
10-28-2010, 5:28 PM
not the detent, as i can easily move the pins. its the actual lower and upper together that creates it being so stuck.

Calif Mini
10-28-2010, 6:10 PM
Use a reamer and be sure to use a mill or drill press and have the part to be reamed aligned so you do not oblong the holes.

The spec for the pin holes is .251" but I try to use .250" to keep things tight.

A drill bit can oversize the hole.

Droppin Deuces
10-28-2010, 6:15 PM
I had one that was a bi-otch to install and remove on my lower, but it eventually loosened up to the point where I can do it with just my hands now. I wouldn't mess with it just yet. How often do you have to take the thing apart, anyway? Just leave it and it will eventually become easier.

bohoki
10-28-2010, 6:57 PM
i used a chainsaw file to open the rear hole slighly on one of my uppers you know "acceptable tolerances" add up sometimes

gun toting monkeyboy
10-28-2010, 9:17 PM
I have an M16A1 upper that is the same way. It takes 5-10 minutes of wrangling to get rear take down pin in. And it only fits on one of the half dozen uppers I tried it on. I figure I'll take it down for a throrough cleaning after I get a few hundred more rounds through it. In the mean time I keep it well-lubed and run a bore snake through it instead of field stripping it down for cleaning. I would hate to take a file to either the upper or the lower at this point. So I will just wait and see if the problem corrects itself.

-Mb

donking
10-28-2010, 10:45 PM
Howdy, I just bought two new uppers and both of them are so tight on my lowers ... I know this is good for accuracy,

Sorry to nitpick, didn't see anyone mention it yet. The upper/lower fit has no correlation to the accuracy. The barrel and sights are all in a fixed position on the upper.

When people are posting about reaming/filing/sanding out the holes, they are talking about the holes in the lugs of the upper. This may not be causing all the tightness as the lugs themselves on the upper may be binding inside on the walls of the lower. Usually just putting the two together and taking apart without pushing the take-down and pivot-pins will be enough to loosen this type of binding. I would do this a few times first to make sure it is not the problem before doing any reaming/filing/sanding of the lug holes.

B yond
10-29-2010, 6:54 AM
I opened the takedown pin hole on one of my uppers with a drill bit VERY CAREFULLY. Now I have some play between the upper and lower, but I have an Accu-Wedge on the way to take care of that, and I'm able to remove the upper with no tools. The slight wiggle between the upper and lower did NOT affect my performance at the range.

lmudave
10-29-2010, 7:26 AM
I had the same issue a few months back with an upper that I could barely get the rear take down pin in and out. I just worked it back and forth a bunch of times until it loosened up to the point that I can just about use hand pressure to pop it out now. Just work the take down pin a hundred times and see if it loosens up, i bet it will. plus the upper is rock solid on my lower now.

Merc1138
10-29-2010, 7:30 AM
not the detent, as i can easily move the pins. its the actual lower and upper together that creates it being so stuck.

Ahh ok, so it is the lugs in the upper. I'd say just leave it. It'll eventually loosen up over time. Want to do it quicker? Repeatedly work it back and forth while watching TV or something. Getting a drill is just asking for problems, at the absolute most I'd polish the inside of the holes in the lugs, but attempting to get the last .001" to get it smoother without having some precision equipment is asking for problems. I used to need a punch(not a hammer) to push my pins through, after a while now I can do it with firm finger pressure.

fcr
10-29-2010, 7:55 AM
Could be the anodizing, if they are of the same company or not. I have that with a few of my rifles. The anodizing eventually gets thinned and the U/L fit really snug. I just had an issue like that with a build I just finished, I went to the source and they said they switched anodizers because of the issue.

Hoop
10-29-2010, 8:03 AM
Just shoot it, it will loosen up over time. It could be that either your lower or upper is out of spec but more than likely it's just a tight fit+anodizing on the pins.

Also don't drill it unless you feel confident you can drill it to precision specs (that is, to 1/100th or 1/1000th of an inch).

dfletcher
10-29-2010, 8:19 AM
Howdy, I just bought two new uppers and both of them are so tight on my lowers I need a punch and hammer to knock the pins out and in to connect and dis connect the uppers and lowers. I know this is good for accuracy, but it really bother me in the sense that if I was ever In a sticky situation or out shooting somewhere with no tools, I would not be able to dissaselble the ars to fix or matinence them. Is there any ways or ideas to lossen up the pins or uppers holes?

I would try two things first.

Shoot it a bit, let the parts settle. If things loosen up, fine. If not, buy the hinge/takedown pins with the raised head, that will allow you to get a bit of purchase on the pins to remove. Between the settling in during shooting and the easier to grip pins, might be just enough to allow removal by hand.

I would think the reason for the tight fit is because the upper is sitting a touch high on the lower, the (rear) takedown pin is hits a bit high in the takedown hole on the stud of the upper. As it passes (gun pointed away) right to left the takedown hole in the upper, being high, and the takedown pin having a touch of wiggle, is "guided high" and strikes the top of the takedown hole on the left side of the receiver. You will probably see scuff marks on the top of the hole in the upper. My approach has been to take very fine "wet 'n dry" paper around a small circular file and remove a very, very small amount of the hard coating - amazing how little needs to come off to make a difference.

Regarding the "it doesn't make a difference" - I don't know, still waiting for David Tubb types to tell us whether their super duper ARs are sloppy or tight fit. I'm not of that type of shooter with ARs, I don't like it because I think it feels cheap. I think while it makes no difference in practical or combat situations having an upper rattle around the rest of the gun can't help when the goal is high degree of accuracy. I suppose I'l also admit to using "bolt action logic" in the matter.

donking
10-31-2010, 3:03 PM
I opened the takedown pin hole on one of my uppers with a drill bit VERY CAREFULLY. Now I have some play between the upper and lower, but I have an Accu-Wedge on the way to take care of that, and I'm able to remove the upper with no tools. The slight wiggle between the upper and lower did NOT affect my performance at the range.

I've tried the accu-wedge for one AR and it didn't work.

I would not recommend using a drill or dremel or any other power tool. Just put it together and take it apart a few times.

voiceoftheright
10-31-2010, 3:37 PM
I wouldn't drill it, I would use a round file on the upper until the hole or holes are opened up enough. Go slow, not too difficult.

donking
10-31-2010, 8:46 PM
I wouldn't drill it, I would use a round file on the upper until the hole or holes are opened up enough. Go slow, not too difficult.

This is the way to go. By "slow" this means to file once then trying fitting them together. If too tight, repeat.

gemini1
10-31-2010, 9:24 PM
I would leave it alone. Just shoot it till it loosens up, if you're shooting at local ranges, they have the tools to help you break down your rifle. Ive shot at Sunnyvale, Cayote point and Jackson Arms. Everytime I ask for help with my pistol or rifle, the ROs are always ready to lend a helping hand.