If you were going to build a defense AR-15, with the best of everything, what parts?

[valnar]

Pictures are a must.

 

[Hacker15E]

I can't love a 16 inch barrel 5.56mm rifle with a short carbine gas system

Why exactly is that?

I've been reading ARFcom and M4C a while, and still can't find a cogent rationale for the love of the mid-length gas system (and the related dislike of the carbine gas system). There is the perception of reduced recoil, and wives' tales of damage to the action because of the gas pressure....

...yet there are a lot of M4s out there getting a lot of use with the military in a combat environment, and nobody seems to be able to produce evidence of this damage.

 

[LawScholar]

Daniel Defense
Noveske
Colt
BCM
LaRue
Magpul Components
Troy Industries

If I was building and money was not an issue, these manufacturers would be my toolbox.

 

[ugaarguy]

...yet there are a lot of M4s out there getting a lot of use with the military in a combat environment, and nobody seems to be able to produce evidence of this damage.

To be fair, those M4s - and the earlier Colt 653 & derivatives - have 14.5" barrels with a carbine length gas system. The longer 16" bbl. with carbine length increases dwell time, and hence increases pressure & carrier velocity. The 16" bbl. mid length gas tube essentially replicates the pressure, dwell time, and bolt velocity of a 14.5" bbl. w/ carbine length gas system (Mist Wolf or others can clarify anything I stated incorrectly, but that's essentially the concept). Of course, the easy solution is to use a heavier buffer to slow the cyclic rate.

 

[rsilvers]

Why exactly is that?

I've been reading ARFcom and M4C a while, and still can't find a cogent rationale for the love of the mid-length gas system (and the related dislike of the carbine gas system). There is the perception of reduced recoil, and wives' tales of damage to the action because of the gas pressure....

...yet there are a lot of M4s out there getting a lot of use with the military in a combat environment, and nobody seems to be able to produce evidence of this damage.

A 14.5 inch should have a carbine length gas - or maybe an inch longer. It is a 16 inch barrel that I was speaking of.

There is no reduced recoil and not sure why anyone would think that. A carbine gas system has more gas port erosion, and a faster rate of fire change over the life of the barrel and earlier unlocking of the bolt while pressure is higher, raising extraction forces. Once you know it is not as good, it makes no sense to want to still do it that way.

 

[12131]

@rsilvers.

Wow. What did the last 25 do that the first 5 didn't do? Just curious....not knocking the collection at all.

By your logic, why 5 when 2, or 1, would do? Folks buy same style gun for whatever personal reasons of theirs.

To rsilvers, I would love to see a pic of your AR collection. And, I thought I was nut about the EBR.

 

[Hacker15E]

A carbine gas system has more gas port erosion, and a faster rate of fire change over the life of the barrel and earlier unlocking of the bolt while pressure is higher, raising extraction forces. Once you know it is not as good, it makes no sense to want to still do it that way.

Again, I see a lot of "talk" about this, but still have yet to see an actual firearm in which this problem has occurred.

 

[kwelz]

And how many high round count guns do you have?

 

[rsilvers]

This is why the M4 needed a different / heavier extractor spring than the M16. The real cure would be to length the gas system. The M4 is close enough with carbine gas that it was generally fixable with the extractor spring change, but could still use an extra inch of gas system length.

Let me ask another way. What is the advantage of raising extraction forces, speeding up bolt unlocking, and increasing gas port erosion?

 

[Mad Machinist]

For a defensive AR......I'd go with a DI .45 ACP. no chance of out of battery discharge like the blowback guns, recoil is non existent, they run cleaner than the blowbacks and even if your foe has body armor...hammer center of mass with 4 or 5 230 grain FMJ's and you will definitely make him/her want to find another task to handle other than bothering you. Here is a picture of one of mine.....CNC guns lower and my design upper reciever......this is NOT a blow back...it is a locked breech gas operated carbine..... On a side note...it is NOT uncomfortable to shoot without ear protection in a social engagement.


and a video of it being test fired

 

[Zerodefect]

The nicest carbine I shot at the last shoot was something like this:

BCM 14.5" Middy with 12" Larue FF rail
http://www.bravocompanyusa.com/BCM-...iver-LaRue-Tactical-p/bcm-urg-mid-14 lt12.htm

PWS FSC566 Pinned Flash hider, some prefer the new Battle Comp 1.5.
BCM bolt carrier group
Mil spec or Gsl 3 gun trigger
Magpul ACS stock
Magpul Moe Grip
Magpul XTM covers
Gear Sector Hand stop
Gear Sector rail sling mount
Magul Sling mount plate
Magpul Ms2 sling
Aimpoint T1 in a Larue tall mount
BCM large charging handle
Stag ambi safety
Noveske Lower (any lower will do)
Stag lower parts kit
H1 or H2 buffer
Magpul Pmag 30
Magpul BAD lever
Troy BUIS
Larue offset QD light mount for G2 LED

 

[kwelz]

Zerodefect has the right idea. It is amazing how much shorter a 14.5 feels over a 16. While there are some minor things I would do different on the gun he linked the core idea is pretty much what I consider the optimal non-NFA defensive firearm.

I would not suggest going with a pistol caliber AR. While they are neat toys, even a .45 is going tofall short of a 5.56 rifle round. If you are going that rout then you may as well use a pistol. Not that a pistol is a bad choice. But it does take away the advantages of using a carbine when you use a pistol round in it.

 

[JustinJ]

I'd say go with a pencil barrel. With the exception of an SPR type rifle i see no reason for a semi-auto civilain AR to have anything thicker. I just bought a Colt LE6720 and plan on improving accordingly to make my ultimate AR:
Troy TRX modular battle rail mid length
YH Flip Up front Site
Matech BUIS
DD single point sling attachment
DD vertical foregrip
YH Phantom Flash Hider for 5.56 Phantom Suppressor
Vltor Clubfoot stock
The stock trigger is surprisingly nice but if i were to change i'd go with a RR

 

[harmon rabb]

If you are going that rout then you may as well use a pistol. Not that a pistol is a bad choice. But it does take away the advantages of using a carbine when you use a pistol round in it.

I'm totally with you. ESPECIALLY 45acp which barely gains anything with additional barrel length.

The point of a rifle is to fire a rifle round. In my own very anecdotal tests, I've fired a 45acp, 9mm, etc vs. a 223 at objects. The different in damage is massive. The pistol rounds don't come close to doing the damage to random junk that 223 does.

 

[rsilvers]

There are not too many good reasons to take a rifle and shoot pistol ammo in it. You lose both power and capacity at the same time.

 

[reeberom]

For parts - in the range of what you describe - quality tends to go with accuracy.
Meaning: CHF barrel, either DD (Daniel defense), Noveske, Centurion, BCM. They will outlast most any.
G&Rtactical will offer you the best quality LPK's, or try AIMsurplus, they have a good deal on DD lpk's. So will Spikes tactical.
Spikes will also have other quality small parts, as does BCM.
When it comes to receivers, both upper and lower, AIM has killer deals on them, from Spikes. These are quality if you don't mind the roll-mark.
In general you really can't go wrong with anything BCM.

What it really comes down to is you doing research, and see who has what in stock.
Enjoy, you will find it to be highly addictive.

FWIW - m4carbine will be invaluable for detailed info when doing a build, especially your first....

 

[madcratebuilder]

To be fair, those M4s - and the earlier Colt 653 & derivatives - have 14.5" barrels with a carbine length gas system. The longer 16" bbl. with carbine length increases dwell time, and hence increases pressure & carrier velocity. The 16" bbl. mid length gas tube essentially replicates the pressure, dwell time, and bolt velocity of a 14.5" bbl. w/ carbine length gas system (Mist Wolf or others can clarify anything I stated incorrectly, but that's essentially the concept). Of course, the easy solution is to use a heavier buffer to slow the cyclic rate.

+1

The 16" may benefit from the middy gas location, but who wants a 16" carbine? I read a lot about the middies not likes low power ammo and choking on it.

If you feel you carbine is over gassed get a H or H2 buffer, it really is that simple.

 

[mortablunt]

A gas piston, 18 in barrel, 7.62X39 or greater caliber bore, Flat top receiver, bayonet mount, ghost right sites. Minimize the number of rails, because those things will add muzzle sweep and a ton of weight, vertical foregrip, flash hider, drug magazine.

 

[gotigers]

Hacker15E

I can't love a 16 inch barrel 5.56mm rifle with a short carbine gas system

Why exactly is that?

I've been reading ARFcom and M4C a while, and still can't find a cogent rationale for the love of the mid-length gas system (and the related dislike of the carbine gas system). There is the perception of reduced recoil, and wives' tales of damage to the action because of the gas pressure....

...yet there are a lot of M4s out there getting a lot of use with the military in a combat environment, and nobody seems to be able to produce evidence of this damage.

Longer gas systems have longer lock/dwell time, less pressure due to more powder being burnt further down the barrel and the longer sight radius due to the FSB being further down the barrel. These effects are barely noticable. The first two listed can cause faster wear on the gun, but the wear would only be noticed after thousands of rounds. The longer lock time slows cycle. This may not reduce recoil, but IMHO it makes the recoil feel "smoother". I like rifle gas systems over them all. I have shot all three gas systems in 3 gun comp. I definitely notice a diference.

Speaking to the statement about midlengths choking on low power ammo. Rifle gas systems seem to have no problem with factory loads, i would guess that this issue would be more a function of the gas port size and/or other components. Maybe with very low FPS or sub sonic home loads.

madcratebuilder
snip

If you feel you carbine is over gassed get a H or H2 buffer, it really is that simple.

+1