FOGeologist

Ah, jeeze, I had forgotten about the rail height issue! With every manufacturer seeking to "solve problems" by creating a varing type of rifle, there are probably myriads of weirdo combinations of components, a sizable number of which could produce guns that either look weird and function fine, look great and malfunction dangerously, or just hardly function at all.

I know you enjoy a protected status on this site due to the knowledge you've acquired. But at this point I am contemplating blocking you, because you act like an child. Kindly get out of my thread.

Roger that, Matt. The key to all these problems seems to be three or four things - buffer tube depth and buffer size, spring rate, gas port size, and gas tube length. The desire to put collapsible stocks on these rifles, coupled with the puzzling desire for idiot manufacturers to make them halfway like AR-15s, and the weird placement and size of gas ports means that everybody gets a shitty experience. That being said, I don't think people should try to build these rifles without reading this site. There isn't that much variation between what works, but seemingly endless confabulations of gear that DOESN'T.

He does seem... kind of autistic. I appreciate his knowledge, but I'm not some dippy 19-year-old kid that needs to be talked down to. I've been turning some kind of wrench for over 40 years on everything from cars to rc airplanes to guns myself. But whatevs. I'll build my gun and see what happens. The journey, in many cases, is more instructive than the final destination. That is the whole point of the thread.

Update: all new parts are on the lower and everything function checks well. The lower is ready to go. The upper is waiting on the correct-length (15.5") Armalite gas tube, as the AR-15 tube wasn't near the halfway point on the cam cutout. I am also waiting on the bedding (0.001") stainless foil which I will thermofit the upper to the extension. Then it's a simple reassembly and test-firing.

So, I bought those parts years ago. There have been multiple iterations of this build. I just found this site and signed up for it a month back or so. All the recent parts I bought before I changed my mind about the buffer system and stock were never installed and returned to the retailers. If I'd found this site over half a decade back when I started this affair, it might have been easier. So it's not like I ignored your advice. You don't have to try to score any points over it.

You ain't kiddin', brother. I may try to keep that carbine buffer & tube, stock and spring... I have an unbuilt Anderson AR-15 upper just sitting around. I could take an Aero blem AR-15 lower ($69), a Faxon Pencil, and buy one of those Toolcraft BCGs and slap together another carbine AR-15. Might cost $350 when all is said and done. Or wait - a 300 Black Pistol!

You know what would be great? If even one word you wrote was wrong. Even a little bit. But it's not. I wish some sort of sanctioning body could set the configurations up to be reliably interoperable and CORRECT. Then a measure of compliancy could be advertised - "this works with that!" Then nobody would buy 2.3 308 ARs to get one working one.

Assuming my assembly and testing go OK, I’ll be buying some magazines and thinking about replacing the Guntech 15” handguard with a nicer 13” piece. What are you using, and why? My Hexmag requires you yank outward to remove it from the well. It’s like they sized it for a different rifle. My P MAGS seem to be OK - they drop free anyway.

After again reading the Gas Tube Post, I resigned myself to buying another part: the 15.5" rifle length Armalite gas tube. Faxon should make their barrels correctly. My AR-15 15.125" rifle gas tube is way short of "center of cam-pin-cutout." Effin' ANNOYING.

Optics Planet has shipped my gear in two separate batches; the pivot pin and Aero Precision rifle-length buffer tube kit has arrived and has been installed into the new lower receiver I like that the pivot pin has a divot in the middle so your pushing tool doesn't scratch the pin, run off, and scratch the lower. Not that this could ever happen to a mega-expert like me. The other shipment with the bolt-catch and stock and takedown pin is arriving today. After that stuff gets put in, I'll take the bolt apart in preparation for the headspace gauges, then I'll foil the barrel extension and thermofit the barrel into the upper. At that point, all should be good to go.

I'm going to avoid adhesives. A shim where an interference fit is created between the barrel and the receiver, until thermofit approach is applied, is the modern way to go. Really, watch the video.

Lol, thanks. I have replaced the upper and lower, I'm on my second barrel, second gas block, second bolt catch, second set of pins, second stock, second buffer tube, fourth spring, second buffer, second gas tube... It might actually be easier to list the parts that HAVEN'T been changed.

In today: rifle buffer tube, spring, buffer, front pivot pin. Still awaiting Midway delivery of buffer tube retainer and spring that flew into the ether and vanished into one of the other 11 dimensions WHEN I was disassembling it. Coming soon: rear takedown pin, Hogue overmolded fixed rifle stock in FDE. .001" stainless metal foil for bedding (Faxon Big Gunner is sloppy in new Aero receiver).

So, a changing philosophy of use means changing approaches. Forget carbine-lengths, weird buffer sizes, adjustable stocks - going rifle length. Fixed stock. Getting missing components and sticking with the Guntec rail for now. The light-weight aspect of this build I am casting aside; any real use of a 30-caliber semi-auto rifle will be a SAPR or DMR role, not something you will haul around. Gonna get it running well, put on a bipod, and use it for precision work. Target weight: Under 12 lbs with unloaded mag. Ordered an Aero Precision fixed A2 length buffer tube, spring, and rifle buffer, an Aero set of takedown and pivot pins, a Hogue Overmolded fixed rifle stock, and an Aero Precision 308 Bolt Catch. Transferring lower parts as we type here.

In! But I won’t borrow it from you, I’ll buy it. Contact me via email and we can arrange meeting and payment.

New wrinkle: Two take-off parts from the small-frame PSA gun aren't able to work out on the M5 chassis: The main pins are the same diameter, but need to be longer as the front ears and rear pin area are thicker on the M5 than the PSA AR-15-width PA-10, and the bolt catch for the .308 is different than the AR-15 size. Everything else seems to have migrated over without concern.

That would be a goodie, too. I have to make that decision on whether I will be dumping the commercial BMS stock/tube to buy a mil-spec stock and tube now. I may just shove more money into the parts cannon to see if I can buy a whole system to replace my old one. But that's going to cost.

OK, update time. Annnnd, it’s complicated. 🙄 I will probably be returning my Spikes Tactical buffer tube when it gets here. It’s too deep, and I was going to replace it with a VLTOR product… Then I measured my existing 7” tube and discovered it was 1.17”, which is apparently Commercial. All VLTOR tubes seem to be mil-spec, and my Battlefield Minimalist Stock is a Commercial stock as well, and I’m looking around at receiver extensions trying to find a 7 5/8” to go with my new 3.25” H3 Armalite and… It’s tough. Alternative: sell BMS stock and tube, return all purchased components and buy a kit from somebody. I could also just go to a standard A2 setup, but the original concept was “under 9 lb 308 AR with scope.” I guess I could also just replace my 3.8 ounce 2.53” buffer with a 5.4 ounce Expo Arms 2.5” buffer, return my Armalite 3.25” H3 5.4 ounce buffer, and stay with my 7” system and use the Sprinco Orange. That would save me some dough.

There seem to be like 8 VLTOR tubes. Which one should I get?

Lol, yes.

New Purchase: Spike's Tactical AR-10 buffer, 7 7/8" long. Purchased from Wing Tactical, $34.50. Now I need the spring. Discount AR15 is out of the Sprinco Red, so I'll have to get an Armalite or a different brand.

This makes sense. It gives you a "lockback" indication which is a function test in itself.

There are sources for this 15 1/4" tube. Don't know if it's worth $15 to fix a problem I am unsure I'm having. Will wait until function test to see if this will be necessary.

Tempting me: Aero Precision Stainless Steel Gas Tube - Rifle Length. It is 15 1/8" long, which would put the gas tube a full 1/2" into the carrier key, as opposed to 3/8". JUST CHECKED: my gas tube is 15 1/8" already. So this is a no-go. Does anybody make a 15 1/4" tube? Is it advisable to use something like that if it can be gotten a hold of?