Trouble attaching an upper to a lower.

[Freebird]

Hey, here's the story. I finished building up my Noveske stripped lower with a stag lpk, miad, BCM stock kit, and CTR. I then attempted to attach my Noveske n4 basic to this built upper. Here's when it goes wrong. I can only seem to pin one side, either the front, or the back. If I use the front pin, the back one will not work, and vice versa.


This is my first AR, so I don't know if I am making some stupid mistake. Hopefully something isn't dimensionally wrong with my parts =[

I'm pretty bummed. I'm supposed to go shooting this weekend.

Edit: Problem solved, used a hammer.

[damndave]

Is it close to being lined up or is it way off? Some are real tight from what I have seen.

[slomofo]

Pin the front one, stick your left thumb underneath the buffer tube and use your fingers to pull the upper down far enough to pin it. Have you tried that method yet?

[thrillhouse700]

I have the same issue with mine. JD lower and Rifle gear upper. If I cock the hammer back on the lower the upper slides right on. Obviously make sure its not loaded. If this means there is something wrong then I am all ears. Seems to work for me so far. I have not shot it yet with this upper tho.

[Freebird]

Is it close to being lined up or is it way off? Some are real tight from what I have seen.

Its fairly close, but the receivers are pretty much pressed together, making me think that nothing will get it any closer.

Slomofo: My first attempt I pinned the front one, gave it a few tried on the back, then pushed the two together then hardest that I could while mambo'ing the pin with my thumb. no joy.

I don't know if it makes a difference, but to release the pin, i have to use a punch. I'm unable to get it out with my hands.

[tommyid1]

I have the same issue with mine. JD lower and Rifle gear upper. If I cock the hammer back on the lower the upper slides right on. Obviously make sure its not loaded. If this means there is something wrong then I am all ears. Seems to work for me so far. I have not shot it yet with this upper tho.

this is because with the hammer up you may be catching the edge of the firing pin as it sits in the rearward position. i always cock the hammer before closing the two halves.

[joelukehart]

Nothing new with an AR. I have a registered Olyarms. I bought an Oly 9mm upper for it in '99 and it is still a bear to get on and off. But I can still smack targets at 100 yards with it regularly.

[ParallaxTactical.com]

Probably holes drilled off-spec. Get a caliper and measure hole to hole on the inside edge. Post your measurement.

[bjl333]

On a couple of my builds I had to do light filing to get the upper to fit. They are still very snug but I can get the take down pin out now. You just gotta figuer out where it is tight and see if more force will do the job or light file work.

[Freebird]

Thanks for the replies guys. Sorry para, no calipers. I'm gonna hit the hay. I'm going to attack this thing full force in the morning.

[jdewolf]

Lube up the pins and work them a lot. I know I have to put a lot of downward force to get 2 halves to mate up. The good news is that there's 0 wobble or movement at all. JD lower and some unknown 7.62x39 upper. At first I literally had to smack the pin with a hammer to get it to go in. After a little lube and working the pin out about 20 times it's still tight but I can at least get it in by hand.

[Jpach]

Where are you located? Maybe someone close by can help you out in person.

[Penzanse]

Probably holes drilled off-spec. Get a caliper and measure hole to hole on the inside edge. Post your measurement.

+1 for this. I have seen this on mine. Hole was off spec. Mine was off on bottom edge.

[erratikmind]

Personally, prior to any assembly work, when I have both the upper and lower receivers available, I perform a dry fit test.

A) Fit the front pivot pin in both the upper and lower receivers individually.

B) Fit the rear take down pin in both the upper and lower receivers individually.

C) Fit both the upper and lower receivers together and note the the alignment of the pivot and take down openings.

D) If the visual alignment looks good, insert the pins for final fit test.

Due to issues in the past, I always perform the above. At any given step, I will have a clear understanding of what the situation may or may not be and what I may be required to do.

You may wish to work backwards and perform these steps. The said may eliminate some of the guess work for you.

I trust that you are able to find the cause and a remedy . . . Good luck.

[RRichie09]

Try putting in the front pin, then flip the gun over so it is upside down and then try to put in the rear pin.

It might just be super tight. By flipping it over you are using the weight of the front if the upper to push up on the rear of the upper by pivoting on the front pin, like a see-saw.