So I’m in the middle of my first 308 build. My goal is to have it under 1 MOA and shoot out to about 800 yards. I purchased an Aero M5 upper and lower and have a Wilson combat 20” barrel and bcg on the way. Rail is a centurion CMR, but I’m trying to see if they’ll let me swap for the mlok so I have a chance of clearing an adjustable gas block. My problem is, the lower is pretty far out of spec. The magazine catch will not catch either of the pmags that I tried. I took some measurements and it seems that the catch slot is too high on the magwell and, thus, won’t let the catch engage the notch in the mag. It looks to be out of tolerance by ~.0105. I used a wood chisel and cut the notch on the mag higher, so it catches now but the rounds/feed lips are sitting higher. Here are some photos (https://drive.google.com/drive/folders/1X314gt4HqSE-psr61gU-5779yOwX2InF?usp=sharing). Question is, I’m now concerned with the quality of the upper and wondering if I should just continue the build once the lower is fixed or if I should bite the bullet on a decent billet receiver set. If I build on the aero, will lapping the receiver face and bedding the barrel extension be likely to get me around .75” groups? Or should I buy a Mega Maten set (not monolithic) or a Grey Ghost precision set? Which one does everyone recommend for the billet receiver set? Can’t find out if ZEV warranties Mega in case there an issue. Also curious who does the machining for Grey Ghost. Anyway, if anyone has a opinion of whether to wait it out with Aero or buy new receivers it is greatly appreciated.
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Aero M5 receiver problems/build questions
- Thread starter fred0311
- Start date
I guess it depends on your budget as well as your patience. If your budget allows, I'd buy a "matched upper and lower". I recently completed a build after not building anything for over 10 years. I was disappointed in how many out of spec parts I gathered recently. Had to go into my old stash in order to get enough in spec parts to complete the build... and it was not a precision build. We are living in a challenging time.
Best of luck.
Hobo
Best of luck.
Hobo
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I have noticed that lately. I guess manufacturers are pumping em out as quick as possible. Thanks for the reply!
I would call aero and let them know what’s going on, I’m sure it’s something that just slipped through qc, they may replace it or give your money back, we use them quite a bit and they’ve been pretty good to deal with.
I had the same problem, The aero parts kit didnt work well in my Aero lower,I had to use both armalite ar10 mag catch and armalight bolt catch. worked great ever since. I'm surprised Aero had not fix this problem on their parts kits, they seem to be pushing off some ar15 parts in their kit, not all parts are interchangable from ar15 to large frame Ar.
That doesn't look like any Aero lower that I've seen.
What are the prints for and who are they from?
What model Pmag are you using?
Taking a chisel to your magazine instead of finding another (proper) solution is a indicator of your mindset.
What are the prints for and who are they from?
What model Pmag are you using?
Taking a chisel to your magazine instead of finding another (proper) solution is a indicator of your mindset.
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I did 2 Aero AR10 builds this year, and had problems with both. The first, a 338 Federal with a Shillen barrel, one of the holes for a hand guard screw was not threaded. I emailed asking them to send me a tap. While they would not send a tap, they did offer to replace my upper and cover all shipping costs. The second was a build similar to yours, 20” WC 308 barrel. I believe the slot for the mag catch was not milled deep enough, and the mag would drop after every round fired. Bent the catch a little, problem solved. Their parts kit too, by the way.
I would try out the Aero set since you already have it. Aero will do the right thing and replace your receiver, just call or email them. In spite of the issues I had with my receivers, both of my guns ended up sub-MOA with a little load development.
I would try out the Aero set since you already have it. Aero will do the right thing and replace your receiver, just call or email them. In spite of the issues I had with my receivers, both of my guns ended up sub-MOA with a little load development.
The receiver is Aero. It just has an American Flag engraving and is called their “freedom” model or something. The prints are from a 308 armorers course that I just completed at SDI. I measured another lower and it matches the tolerance in the prints. The main thing, though, is not to get hung up on the accuracy of the prints, my lower will not accept either of the two pmags I tried. I ordered a lancer and a hexmag to try those but it will be a few days for shipping. My mindset in chiseling the mag was not to find a permanent solution, but to confirm what I could not see with my eyes—that the catch is too high in the mag well which won’t allow the catch lever to engage the notch in the mag. I already threw the mag in the garbage, it was just a 10 dollar test “tool”. Academy has about 50 more of em last I looked. It’s the gen m3 lr/sr 10 rounder that Aero sells on their website. I am new to the Ar-10/LR 308 platform though so if Aero is not compatible with pmags then is there another brand that works. I submitted a claim with Aero, when I tried calling there was long hold times. Ultimately, at this point, I’m leaning toward just buying a better receiver set. My only question is how many people have had luck “bedding” the barrel extension with lock tite and how easily is the residue removed from the barrel extension if one decides to disassemble it later. Thanks and Semper Fi!
Awesome! Thanks for the help. Did you do any tricks like bedding the barrel extension or facing the receiver on your builds? Criterion recommends it in a video series but I didn’t know if it actually improves accuracy.
I’ve used a few Aero uppers and lowers now without a problem, but I did have a issue with out of spec pins on one of their parts sets, their customer service is very good I would just give them a call.
For what it's worth, my Aero M5's measure the same as yours and they work fine with Magpul mags. Just a data point for you, not suggesting anything more than that.
No problem. I did not bed the barrel extension or face the upper, but I did intend to if accuracy was not acceptable. The 308 is easily a 1/2 MOA gun, the 338 Federal is about 3/4. I use both for knocking over wild hogs, so that’s good enough for me.
I have had good luck with Aero, so far. I’ve done a 300BO pistol, 5.56 pistol, and an M5. I definitely want to upgrade triggers in all three from the mil-spec triggers, they function fine, I would just rather upgrade. Tech support at Aero advised me not to use lock-tite or anti-seize when installing barrels into their uppers. I did go with BA barrels though, which is also Aero. YMMV
Thanks, that’s good to know. Maybe I got some unlucky pmags? I may have already posted it (can’t remember) but I picked up a few more 10 rounders and a couple of twenty rounders over the last day or two. It works fine with the twenty rounders and 2-3 out of my 5 10 rounds Mags work now. Maybe just a fluke. I’m excited to see how the lancer works. Thanks for taking the time to measure
Sounds good! I may forgo it and just assemble it first to see how it shoots. My barrel is coming in tomorrow.
From what I’ve been reading, Aero is mostly solid on the AR-15 platform it seems like it’s the M5 that people gripe about. That being said, I just completed a 80 percent lower and used Aero everything for the upper as part of the SDI program. I test fired it a couple of days ago and it chewed through 50 rounds without a hiccup (not a huge count but reassuring). I put a Geissele SSA in this build and I think it’ll serve me well. Interesting about not using anti seize on the barrel extension, though in reality it probably really isn’t necessary.
