rpoL98

more RTB, similar forging as APF:

RTB 80% lower:

definitely a lot of beef on that lower...

@haroldi'm sorry, what brand of semi-auto 308 is "apf"? I thought maybe Aero Precision, but they don't have an "f" in their name?

you know you're replying to a 2016 post? necro-post?

here's another one that required file-to-fit modification at the buffer tube upright: Aero M5 upper RTB forged DPMS-pattern 308 lower, file-fit modified to accept Aero M5 uppers so, I guess, some fit, some don't. I guess it comes down to the company doing the final machining on the forging (or billet). Hmmm, interesting. I purchased some of the Noreen forged lowers directly from Noreen, and other Noreens from RTB, and then this DPMS-pattern forged lower also from RTB. I don't have any AR-308 DPMS-pattern billet lowers to compare. And I don't have anything genuine DPMS original. I'm posting the mainly pics to show the differences between the forged 308 lowers.

the AR-308 in the above picture uses a Faxon 16" Gunner barrel which is listed as "mid-length" gas system length, but in actuality uses the Armalite AR-10 carbine gas system length. The Armalite AR-10 Carbine gas tube is about 3/8" longer than the AR-15 mid-length gas tube, enabling use of AR-15 mid-length drop-in handguards in an AR-10 platform. this is all due to the taller barrel nut, evidenced by the bigger delta ring.

Aero M5 upper Noreen DPMS-pattern 308 lower, file-fit modified to accept Aero M5 uppers

@strawf3 you need to use a barrel that uses the Armalite AR-10 gas tube length. I suspect your friend's barrel is one that uses the standard AR-15 gas tube length. for comparison, the AR-15 rifle gas tube is 15-1/8", the Armalite AR-10 rifle gas tube is 15-1/2". the extra gas tube length means the gas port is that much further forward, and consequently the gas block and hand-guard cap is also that much further forward, enabling use of AR-15 drop-in handguards. as an example, Faxon AR-308 barrels use the Armalite AR-10 gas port location, instead of adapting the AR-15 gas tube to their AR-308 barrels.

personally, I've found that Aero M5 uppers will not fit to DPMS-pattern LR-308 lowers. You can get the front pin in, but the back pin won't go, the upper doesn't seat down low enough, there is upper-to-lower receiver interference at the buffer tube upright curvature. It's close enough that you could probably pound the pin in with a hammer and some grease, but then you're probably deforming the aluminum around the holes, for both the upper and lower. I file-fit my DPMS-pattern LR-308 lowers so that they fit my Aero M5 uppers, get the coated after that, since I've standardized my AR-308 pattern on the Aero M5 receiver set fit. I've worked with a several different DPMS-pattern LR-308 lower forgings, it's been consistent. However, DPMS-pattern LR-308 uppers will fit onto Aero M5 lowers no problem.