New upper and lower impossibly tight

[coolarthur1]

Aero X15 and an aero upper. The lower is the new piece in this equation, its so tight i actually have to use a nylon hammer to get the pins in and a punch to get them back out.

Trying 2 different uppers, same problem. So I think this lower is a little weird, or maybe its just the pins?

When i place them together pins out, there is a slight gap between the 2

[therealnickb]

I have a Les Baer varmint the requires a tool to move the pins. But it shoots one hole groups at 100 yards. (Sub .5”) I’m not messing with it.

[HerrNuguri]

Can you put front pivot pin in your lower while the upper and lower are not closed? If so the problem might be the rear of your lower. I suggest take a look at the rear lug of it. See if you can find any scratches on your upper/lower, wherever the scratches are they are not fitting well.

[coolarthur1]

Can you put front pivot pin in your lower while the upper and lower are not closed? If so the problem might be the rear of your lower. I suggest take a look at the rear lug of it. See if you can find any scratches on your upper/lower, wherever the scratches are they are not fitting well.

I can put the front pin in without issue, the rear wont fit without hammering.

I can also put the rear pin in without issue, then the front needs hammering.

There really arent any marks or scratches anywhere.

Ive also tried it without the bolt and buffer, no luck

[bugsy714]

[coolarthur1]

Yeah not even close to breaking the surface. I think its just out of spec. Its like this on all uppers

[DesertDave100]

I've built about 6 AR's, mostly from 80% but one with a finished Aero lower. If memory serves, every combination of upper/lower required some tapping with a nylon hammer to assemble, and punch to remove the pins. At least for the first few assembly/disassembly operations. Now they all have no issues with finger pressure.

I don't know if this is 'normal', but for me it is.

[Barang]

most of my receivers are aero and i have one that's like yours. i altered the hole (take down) a tad and it's now fine even after 7 years. i'm sure i'm the only one who did this so "don't be that guy."

[Oldmandan]

Round file, file it a little

[FeuerFrei]

Aero X15 and an aero upper. The lower is the new piece in this equation, its so tight i actually have to use a nylon hammer to get the pins in and a punch to get them back out.

Trying 2 different uppers, same problem. So I think this lower is a little weird, or maybe its just the pins?

When i place them together pins out, there is a slight gap between the 2

Lower is out of spec. Any AR clone lower should be able to push the pins without the use of tools unless it's just a bullet tip. Field stripping etc.

The holes are 1/4" dia and you can check alignment with the pins out. You can use a 1/4" drill bit to clean up the holes with an upper attached (do this by hand only, sans hand drill).

Add on coatings can cause pins to stick too. That would be lucky if that's all you find.

I don't recommend using a hammer to repeatedly move steel pins on a thin aluminum frame. It's not designed that way.

Tight upper to lower fit doesn't mean squat to accuracy.

[MarikinaMan]

I recommend applying grease on the channel for the detents thats on the takedown pins. Make sure to get into into the detent spot in there. Cycle them a few times and call me in the morning.

A rough finish or flashing or simply being dry in that channel can make those pins hard to move.

[coolarthur1]

Ok what ive noticed is the upper and lower require a significant amount of force to close on each other.

When you put one pin in you have to squeeze the upper and lower together a ton and simultaneously drive the pin in with your thumb.

I greased the pins, I even used different pins. I think the lower is just out of spec, not a huge deal, maybe shooting it will loosen it up

[MarikinaMan]

Ok what ive noticed is the upper and lower require a significant amount of force to close on each other.

When you put one pin in you have to squeeze the upper and lower together a ton and simultaneously drive the pin in with your thumb.

I greased the pins, I even used different pins. I think the lower is just out of spec, not a huge deal, maybe shooting it will loosen it up

The upper and lower are metal. You cant squeeze them together unless you have some sort of tensioning insert in there or a nylon tipped fitment bolt thats not adjusted properly.

[edgerly779]

Better tight than loose. I finished and registered a bunch of 80% and some I had to lap in. They outshoot my spikes and LRB lowers everytime. Even my
colt lower has a hard time keeping up' . I ran a .246 reamer thru holes with some fine marvel magic oil which use on bolt body and internals. Randall helped me with the fine print.

[coolarthur1]

The upper and lower are metal. You cant squeeze them together unless you have some sort of tensioning insert in there or a nylon tipped fitment bolt thats not adjusted properly.

theres no wedge and the nylon screw is bottomed out, its not even close to the surface