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Posted: 1/8/2026 3:26:59 PM EDT
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So I picked up this upper from Atlantic to use on my Aero M5 lower I already have built. I don't know much about AR10 compatibility other than there are issues with brands and generations so I tried to research it the best I could and everything I came across lead me to believe that a DPMS upper should fit on an Aero M5 lower... Well the upper came today, and I can just barely mate the upper to the lower but I have to tap the takedown pins in with a rubber mallet, and when it's together, the BCG is locked up tight. So, color me confused. Am I mistaken or have I done something incorrectly? |
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Unlike AR15's... There are NO MilSpec guide lines for Large Frame AR's. So while it may be a "DPMS" pattern, that does not mean different manufacturers parts will fit / function properly together. Welcome to the "fun" of LFAR's. ( No Offense intended ) If your linked DPMS upper is a currently produced model, It is most likely a PSA "DPMS" patterned upper. ( And your link sure looks like a PSA ) FWIW, PSA bought DPMS a few years ago. There are slight differences between the various "DPMS" pattern manufacturers ( as you have now seen ) Your options are basically sell the upper, or buy a PSA PA10/ PA65 lower. Ang a, again not trying to sound like a prick... just a painful truth. |
*Hold on to your AR-15s. Their magic must be very powerful, or they wouldn’t want them.*
JAFOM.... Just another fat old man.
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TOGC,IADC
JAFOM.... Just another fat old man.
________________________________
TOGC,IADC
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does it matter if the receiver is high or low? if your DPMS LR-308 receiver is low or high profile , you can follow this measure the height of the tab that extends above the charging handle. A low-profile receiver measures 1/8 inch, while a high-profile receiver measures 3/16 inch. If the tab is larger than 1/8 inch, it indicates a high-profile receiver. my 2 # LR308 i have now are both high 3/16 i went and found the gens here the high profile (or Gen 1) has a 3/16″ tang, while the low profile (or Gen 2) has a 1/8″ tang. |
All Gave Some / Some Gave All
Maj. Richard Ayers
4-16-70
http://www.pownetwork.org/bios/a/a048.htm
Maj. Richard Ayers
4-16-70
http://www.pownetwork.org/bios/a/a048.htm
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Originally Posted By Bearcat24: You have to buy the pins from AERO. I went through this with my KAK upper years ago. I'm at the point where I might just get a PSA lower kit and build another gun |
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These new DPMS lowers and uppers are not the same designs as the original ones. The original DPMS uppers fit on an Aero lower, but there was a small gap where the radius portions of the receivers mated. The opposite was true for an Aero upper on the DPMS lower. The upper would mate with the lower before it could sit completely in/on the lower. These new DPMS uppers could have a different radius cut to them. They may be slightly longer. You're going to have to exam the fitment closer to see where the issue is. The first thing I'd check is the tension screw in the lower. Make sure it's not protruding into the lower and keeping the upper from seating all the way down. If that's good, I'd remove the receiver extension and see how the upper and bcg align with the lower and where the mis-alignment is happening . If you conclude that they're incompatible, honestly, I think your best option would be to buy a DPMS 308 lower from PSA. They have them for around $299 for a complete one. Then you can buy or build another upper for your Aero lower, as you stated earlier. |
| My pins were DPMS standard pins. Had issues with them fitting correctly on the aero lower. I contacted them about it. Was told I had to use theirs on their lower due to dimensions was a little different the standard DPMS version. They were right. Ordered theirs, fit right in without issues. Go ahead and email them. Be specific if you do. |
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