# New Rock River lower receiver



## Frank45 (Feb 21, 2010)

I was able to secure a new lower receiver and a Panther Arms lower parts kit for $150. I thought it was a good deal. So now I'll be building my first A-( something). I not sure what path I'll choose in building this sucker, but it'll be fun. I spent the afternoon at Brownell's web site checking out the video's on the introduction to this type of weapon. Soooo much to choose from. All I know is I'll start out with the A-2 stock, flat upper. Barrel length?No clue.Cabliber? No clue. Having access to a machine shop may have some advantages. So maybe some custom parts? So much to think about. Anyone want to speak their mind on my new prodject? :smt070


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## DJ Niner (Oct 3, 2006)

Nowadays, I'd say that was as smokin' deal.

As for the caliber, unless you have a specific need for a larger caliber, go with .223/5.56mm so you can afford to shoot it and have the largest selection of accessories. Same thing for the barrel; if you have no specific need for a heavy barrel, get a light one (the lighter the better, IMO). I'll offer similar guidance on the barrel's length; unless you need a certain longer length for velocity or shooting competition reasons, go short. It'll bounce a bit more when fired, but it's not like that caliber is gonna brutalize anyone. Short (16"), light, and handy in .223/5.56mm semi-autos is the way to go, IMO.


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## Frank45 (Feb 21, 2010)

Now If I understand correctly you can shoot the .223 in a 5.56mm but 5.56 in a .223 because of pressures are higher in the Nato round. The barrel I thought at 18" would give a little more distance? Or should I should ask is,at what distance will a 16" barrel be accurate to?


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## SaltyDog (Jan 1, 2009)

Frank you are correct about the 5.56/223 use.

From Wikipedia



> The 5.56 mm NATO chambering, known as a NATO or mil-spec chamber, has a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 Remington chambering, known as SAAMI chamber, is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber (Rock River Arms)[14] or the ArmaLite chamber, which are designed to handle both 5.56 mm NATO and .223 Remington equally well. The dimensions and leade of the .223 Remington minimum C.I.P. chamber also differ from the 5.56 mm NATO chamber specification.
> 
> Using commercial .223 Remington cartridges in a 5.56 mm NATO chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223 Remington chambered gun due to the longer leade.


The 16" barrel is the shortest legal barrel you can have without a federal license.

If you move up to an 18" barrel it will improve the accuracy a little but also slow down the bullet.

The 5.56 with a 16" barrel would be good out to 500 meters easily.

Also I recommend - Short Stroke Piston - for the upper.


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## Frank45 (Feb 21, 2010)

SaltyDog said:


> The 16" barrel is the shortest legal barrel you can have without a federal license.
> 
> If you move up to an 18" barrel it will improve the accuracy a little but also slow down the bullet.
> 
> ...


Over a 1/4 mile is decent I don't have a problem with that. Although windage on that wieght projectile must be close to impossible to calculate for the layman. Now the piston you are talking about is for the gases I'm assuming,and from which I understand is a very effective way to cycle the weapon without the hot gases and crude gumming up the works,as the blowback system will do. Good deal. I understand the new milspec rifles will have this incorporated in them. Has anyone seen the laminated wood stock kits for these little guys? $150. I'm between it and the skelitonized stock. I like the wood only because it makes it look like a regular rifle instead of a "terrorist or militia" weapon. Not that I should care. Anyway thanks for the time you gave me.:smt023:smt023


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## Poink88 (Feb 11, 2010)

Read this...

http://forums.officer.com/showthread.php?t=81462


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