7075 aluminum...The barrel is 4140, not the 4150 with the vanadium in it, but hammer forged barrels are available, which I would prefer over the 4150 myself. Its an excellent shooting rifle. I forget the size of the port hole where the gas tube meets the barrel, but it's a little smaller than the Colts that were issued. FN told me their hammer forged barrels were mil spec over the phone, which I'm really not sure, but THINK it would be the size Colt uses. I would want to verify it before betting on it though. But I can attest to the 20 inch FN15 rifle shooting flawlessly.
I finally put a few rounds through mine and I can say rocks. Wasn't exactly what I was looking for but I traded for it straight across with an old problematic rra I had in the safe. The barrel isn't chf from what I read, but it is accurate and runs like a dream. I might put a DD 18" on it with some rails, not sure yet. Gotta have room for a flame thrower and positron collider after all.
The only things non-milspec on an FN15 Carbine and Rifle (not counting the new Sporting Series or whatever FN calls it) are:
1. Barrel - 4140 button broached chrome lined instead of 4150 button broached chrome lined. Contrary to popular belief, M16/M4 barrels are not hammer forged per MILSPEC. They are button broached. Don't believe me, hunt up the M4 TDP.
2. The castle nut on the FN15 Carbine (obviously not applicable to Rifle) is not staked.
4140 chrome lined steel is plenty good for civilian application. 4150 would come in handy if one were to rock n roll that mutha all the time. However, if you can afford an NFA gun and the ammo to shoot it on full auto that much, you can afford to buy a new barrel without losing any sleep. Lest people forget, BAR and Garand barrels were 4140.
Non-staked castle nut? Once again, big whoops. Take a hammer and chisel to it.
I know that some people criticizes HK MR556 for having a non-chrome lined barrel versus the HK416. To me that's also stupid. Big whoopdedoo about chrome lining if your gun isn't shooting corrosive ammo or on rock n roll.
I tell you guys this much, even though the FN15 Carbine and Rifle are basic guns they still comparable favorably against the Colts. The quality of FN fit & finish is evident when you examine the two rifles side by side.
Correct Fnfalman...the mil spec is 4150 non forged barrel, but I would shoot the 4140 barrel that comes from the factory until it wore out, which would be a lot of rounds - it's still a good barrel....but would upgrade to the hammer forged barrel if and when I shot the 4140 barrel out. I'd just skip over the 4150...The 7075 aluminum receiver indeed has a better finish than Colt's too. Port sizes...I had to call FN because couldn't find the info in print..and forgive me but forget the size he told me...but was slightly smaller (on their 4140 barrel) than I had found listed for Colt. But information given out over the phone isn't always gospel.
The FN commercial AR style rifles and carbines are not made from the TDP thus not MILSPEC. It is essentially a nice backwards engineered rifle that shares no common parts with the mil contract rifles like the Colts Defense rifles do. They are produced on a separate lines and not cross pollinated.
So if I was looking for a good solid AR for my wife that wont break the bank, I should consider the something from the FN Series of AR 15's (but perhaps not the Sporter) ? I really like the FN 15 Rifle so far. It shoots much smoother than the DD 16" thanks to that awesome rifle length gas system. I will probably make a few upgrades like throwing on a free float rail, maybe a chrome finished bcg, and keep the stock one as a backup. I imagine you guys would probably recommend an FN CHF barrel if and when i get around to putting one on. For the longest time I planned on purchasing a DD SPR, but this rifle was a deal I couldnt pass up. It also provides me with a solid base to build off of, adding the components I want. Overall I am happy with the trade and am looking forward to putting many a round down range. Thanks for all the info guys!
Thank you for the additional information. The material is 7075-T6 on both.
FNH USA Customer Service
From: Coy Greer [mailto:[email protected]]
Sent: Monday, August 25, 2014 3:31 PM
To: FNHUSA Customer Service
Subject: Re: FN15
The receiver extension is also referred to as the "Buffer tube". Some manufacturers produce this part out of 7075 type Aluminum alloy, and some manufacturers produce this part from a 6064 type Aluminum alloy. What type of Aluminum Alloy is FN using to produce this part on their FN15 rifles and carbines. 7075, or 6064?
From: FNHUSA Customer Service ([email protected])
Sent: Thu 8/28/14 2:18 PM
Thank you for your interest in FN products.
Please see the answers listed below.
BOLT CARRIER GROUP
C158 or 9130 Bolt? Carpenter 158
Shot Peened Bolt Yes
High Pressure Test (HPT) Bolt Yes
Magnetic Particle Inspection (MPI) Bolt Yes
Extractor Spring Insert Yes
Auto Bolt Carrier Yes
Staked Gas Key Yes
Barrel Steel 4140
Port size .062"
High Pressure Test (HPT) Barrel Yes
Magnetic Particle Inspection (MPI) Barrel Yes
Chrome Chamber and Bore Yes
5.56 Chamber? Yes
M4 Feedramps Yes
"F" Height Front Sight Base Yes
Taper Pins at Front Sight Base (FSB) Yes
Parkerized under FSB? No
1.14" Diameter Receiver Extension- 7075? Mil-Spec Dimension: 1.14", 7075 material
Staked Castle Nut Not currently, lock-tight
"H" Buffer No