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Discussion Starter #1
With an Aero M5 upper is there a specific pattern of 308 barrels that are required? Since there isn't a mil spec to go off of. What are some recommendations for the best 20 inch AR10 barrel? Also, are there specific handguards that only fit with the Aero M5? Preferred to either get a MLOK or Keymod type of handguards. What are some recommendations for handguards to mate with that upper?
 

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OK,, first off, "AR10" is an Armalite Pattern rifle.

Yes, people use the term interchangeably to mean "308W-size AR type rifle".

Don't be That Guy and add to the confusion it causes.

I'm not being a picky jerk, the Large Frame AR world is sufficiently "non-standard" that details like this MATTER.
There are basically 4 or 5 INCOMPATIBLE standards, the AR10, the DPMS LR308/SR25 (same), and a few other proprietaries.
The SR25 has the most "aftermarket" support for modularity of parts you may want.
Armalite is ALMOST the sole source of AR10 parts, they will be expensive.
The other proprietaries, are exactly that, proprietary, with very little "outside" support.

Now, the Aero Precision M5 is a DPMS/SR25-pattern receiver.
As such, it uses LR308/SR25 Uppers/Lowers (match whichever half you have/get), Barrels, BCG's, Buffers, standard AR15 triggers, buffer tubes, P-Mags.

The AR10 (Armalite) receiver halves DO NOT MATCH UP to SR25 receiver halves, also the Buffer, BCG, AND Barrel Extension are different.

AR10 barrel nut is not the same as the SR25 barrel nut, no mixing fore-ends either.
No mixing bolts and barrels unless you want headspace issues to fix.

I have built 2 SR25's over the last 5 years or so, both used KAK BCG;s, Rainier Match barrels (18" Hog Killer and 22" Target Clanger).

I prefer Keymod handguards, harder to find (damn M-Lock's are everywhere).

Worst trouble I had was the first one was built on an upper whose rail was "DPMS-High" standard. I played merry hell trying to find a KM fore-end that was DPMS High for the rail.
DPMS Low is newer (was new about the time I built that rifle), a lot more fore-ends for it it seems.

So, IF you insist on the rail of the fore-end matching evenly the upper receiver rail, read closely and determine exactly what you need.
 

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Discussion Starter #3
Thanks for clarification on the nomenclature of the large AR platform rifles. I have a DPMS Gen 1 lower and the M5 aero upper. What has been the best matching keymod or m-lok handguards for that upper? I really wanted to get the Aero 20inch heavy barrel, but that doesn't seem to be in stock anywhere. Do you have any recommendations for 20 inch barrels?
 

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Well, again, if you look at Aero's website, in the specifications of the Upper, it states:
"DPMS High Profile (.210) Tang "

So, if you want it to match, you need a fore-end that is made to "DPMS High".

You will have better luck searching if you search using the term "LR308" instead of 'Aero M5', because the DPMS term has more history so is more commonly used as a generic term.

If you search "dpms high profile handguards", start about the middle of the first page and go down from there, page 2, 3, 4, etc.

You need to decide what length you want, beware that a handguard long enough to hide the gas block MAY REQUIRE WORK TO NOT TOUCH SAID GAS BLOCK.

The only way to be able to expect to avoid this is to buy the handguard from the upper or gas block maker (hoping they fitted this in design).


Also, I have heard of many cheapo handguards "slipping" on the barrel nut, basically the rifle is supported by the fwd. part of the handguard and pretty soon it is laying against the bottom of the gas block.
Preventing this requires a decently designed handguard.
The one on Hog's Bane has circumferential grooves milled in both the nut and the guard, that clamp together.
The one on Rainmaker has the handguard actually thread onto the nut, and is locked by a "jamnut".
Both hold quite rigidly.
The ones on both .223's have very long nuts, lots of bearing surface for the guard to clamp around (but not grooved), no problems with those YET........


Barrel:
Same thing, "LR308 Barrel 20 inch" , page after page of search results, you have to decide what is available, what profile you want, and how much you want to pay.
Parkerized 4150 alloy
416R Stainless Alloy


My Hog Murderer is an 18" "normal-weight" barrel, 1:11.25".
My "Range Toy" long reach "sniper" rifle is a 20" SDM profile barrel, 1:10". Both Rainier Match, Stainless.



save yourself 2 problems.

NO ALUMINUM GAS BLOCKS.

NO SETSCREW-RETAINED GAS BLOCKS (steel, clamping-type, gas blocks).
Every AR I ever built (4 now) use JP Rifles Adjustable Gas Blocks. .308 AR's should never have a wide-open gas block anyhow, need adjustable.
Yes, they cost, and they eliminated many well known problems.

Do yourself and the rifle a favor and do not go Carbine Length gas system on a .308...... Rifle Length.

Ignore the above at your own peril.




Also the 2 rifles above, Bane wears a JP Recoil Eliminator, the other, the M4-72 brake, both are excellent.
 
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wow, just wow...the things known, unknown, deciphering?
getting older very hard! you the man<><Dan
 

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Discussion Starter #6
Will this work or mount on the M5 Aero Upper?




Here is the upper I have:

Also, what nut should I pick up?
 

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Fore-end/barrel nuts will come with the fore-end. Buy the correct fore-end for the upper (SR25/AR10/etc.).

You don't "pick up barrel nuts" separately.
 

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"Will this work or mount on the M5 Aero Upper?"



shockme,,,,, read the bottom of the page!!!!!!

"AERO PRECISION HANDGUARD IS NOT COMPATIBLE WITH M5 .308 PLATFORM. "

AR15 handguards DO NOT FIT AR10/LR308/SR25 rifles, the .308 barrel & extension is bigger diameter, the .308 receiver is bigger diameter to accept the barrel extension, the barrel nut is bigger in diameter.


The ONLY "AR15" parts you get to use on a SR25/LR308 rifle, are as follows, NOTHING ELSE:

Trigger mechanism
buffer tube
stock & pistol grip
bolt catch
magazine catch
gas tube
In SOME CASES (depending on barrel diameter at the gas block location) Gas Blocks


That is it.
Everything else that has to address a 2.8" long cartridge (2.25"), a 2" long case (1.75"), a .470" diameter case body (0.320"), a .30-caliber barrel bore (0.22), a .30 caliber projectile (0.22), a 62,000-psi cartridge (55.000psi)., are .308-class AR Specific.

Lower Receivers and magazines (2.8" cartridge)
Upper receiver (longer lower receiver)
Receiver disassembly pins (wider receivers so longer and wider diameter pins)
Dust Cover (larger ejection port to permit .470" 2" long case to leave)
Charging Handle (longer receiver, longer stroke)
Bolt and Carrier (longer receiver, wider bolt head)
Buffer (longer carrier stroke in the same buffer tube)
Buffer Spring (greater cartridge power and heavier BCG)
Barrel with extension (wider bolt locking lug area)
Barrel nut/fore-end (wider bolt extension)
Brake/Flash-items (wider bore, wider projectile, wider barrel threading size)
 

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Discussion Starter #9 (Edited)
When building a rifle length AR-10, can a carbine length buffer tube be used with a rifle buffer? I'd love to put a telescopic magpul skeleton stock on it
 

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No, you can NEVER use a Rifle Length Buffer in a Carbine Tube, Not in an AR15, not in a .308-class AR.

Rifle buffers are significantly LONGER than Carbine Buffers, because the Rifle tube is long enough to accept it.

A Rifle Buffer in a Carbine Tube WILL stop the bolt stroke short.

Carbine Buffer, 2.5" long.
Rifle Buffer, 5.3" long (Aero), 2.8" longer, 2x as long, plus a bit.

Rifle and Carbine ALSO use different springs.

The ONE WAY you get to "interchange" is IF you spend the money on the JP Rifles Silent Captive Spring System.
The spring assembly fits in a carbine tube.
The spring assembly, with a nylon spacer (included with it) fits in a Rifle Tube. The spacer takes up the length difference between the tubes.
No, you CANNOT use the AR15 Captive Spring System in a .308-class AR, you use the LR308 version. Longer assembly and heavier spring.
 
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