im having a boring issue, its currently on my AR308
so what happens is; i just installed the takedown pins on my AERO lower and once i drop the upper in and lock the FRONT takedown one, somehow its getting misalligned…causing the magazines to get stuck in place, and making it impossible to
insert/remove a magazine with the bcg installed.
HOW THE HECK IS THIS POSSIBLE? someone here is making their components out of specs? it is the first time im running thro a similar issue with more than 9 builds. Any suggestion? get a new pair of takedown pins?
from the naked eye is virtually impossible to spot any weird canting of the upper to cause this problem once the takedown pin is closed
Pictures help. Are both upper and lower made by Aero Precision, or is the upper a different brand? I ask because not all .308 AR parts are compatible with each other.
Also, since this involves a .308 AR it’s a perfectly legit post in this forum. I would delete the sentence implying it’s in the wrong place just for attention.
Yeah, that would bug me too. Without photos I’ll need a really detailed description. Are both front and rear pins* installed in the lower and being put through the respective holes in the upper’s lugs? Is it difficult to close the two halves, or to push the rear takedown pin to the closed position?
*the front pin is the pivot pin and the rear is the takedown pin. The terminology doesn’t usually matter and they both get called takedown pins all the time, but to be sure I’m understanding the problem be precise.
What kind of magazines are you using? How far will they insert before being blocked?
Just to confirm, the same magazines will go in and latch properly when the lower half is separated?
Im using 25 rounds p mag, i have another AERO 308 build and they fit great and drop free when releasing the mag catch.
i have tried with the lower alone (no upper inserted) and the mags fit as they should & drop free, i also tried fitting the other upper into the incriminated lower and im getting the issue again, so there is something wrong with the lower 120%
(other upper in the good lower works as it should)
the pins definitely require some pressure to be closed (not a big deal in my opinion, on my ar15s i have enlarged pins that require literally a little hammering to get them closed & open, they all works perfect)
pins goes through the respective holes… THE ONLY difference, would be on this build im using DPMS 308 pivot & takedown pin, while there should be 100% compatibility, it could be the problem… i have to say that the fitting is definitely not snug and
there is quite a good amount of wobble to leave space for some “tolerance” so wtf???
if it wasnt hard as hell to install/uininstall the front pivot i would try swapping the pins from the other one and test them.
i want to repeat that testing this build with the pivot pin disengaged will make it work, as soon as i lock it in place the issue pops up.
Can you insert the magazine with the upper & lower pinned and BCG installed with bolt in battery?
Sounds like the upper receiver is mot properly machined and the magazine is binding when it enters into the upper receiver.
Yeah, it sounds like the new lower is out of dimension somewhere, like in the location of the pivot pin hole or the height of its upper surface. Either way, I think your best next step is to call the manufacturer and explain the problem. FYI they will probably want to see photos too before issuing a call tag or RMA, whatever they might do. But it sounds like a machining issue.
I wouldn’t bother, personally. If the pivot pin slides left/right freely when there’s no upper lug there, and it appears to be straight and of correct size, it’s not likely that it is the issue.
DPMS pins as expected are not the problem cause, swapped them with aero ones and im still having troubles, looks like HK was somewhere close to the issue, testing with the upper inserted & pivot pin closed, magazine inserted, moving the upper up and down,
it seems the upper is pushing on the magazine, causing it to rock just a little forward and build some tension (enough to kiss it too hard lol)
again, upper works perfectly fine on another lower so i guess the hole must be a tad too low on this one… should i sand the upper a little? can this affect allignment and cause issue with feeding ext ext? im definitely disappointed with AERO.
okay taken some very closeup pictures of both assembly, i hope the website shows them properly
so it think this confirms that this lower is “defective”, at least it have the pin holes drilled just a hair back, probably enough to tighten things up.
now… i think a tad of filing wont be a big deal? being an international user, any kind of RMA will take a freaking while… im extremely disappointed tho.
Looks like a pretty big machining error. I don’t think “a tad of filing” is going to fix this.
Where are you? Who’s the Aero importer for you? Do what you like but I think you are giving up any warranty claim if you try to file on the lower to fix the machining defect.
Will have to go through Brownells for the RMA… but lower is registered as a firearm main component, it would require hell of alot of papers to get the lower anywhere outside my hands… i would be unhappy to touch the upper which is not defective… but nothing
filed down a little portion of the highlighted zone in the upper, the edit except for the finish stripped out is basically invisible to the eye, seems to have worked good and now mag (tried only p mags) drop free & dont lock in anymore.
not happy to have been forced to touch the non defective part, but at least now things seems to work good.
