80% ar15 Quick Question

[acj415]

I been reading about making a ar15, but not too clear what is the different between the calibers of the weapon? I see some 5.56 or 7.62x39 parts kits, but is there a difference when milling out the lower; or it just the internal parts?

[luckylogger6]

7.62x51(308)? Its an ar10 and is a different lower than the AR15 in 5.56x45mm

[Centaine]

Lowers would be the same, however a 7.62x39 ar15 type of rifle would most obviously utilize a different upper, different bolt carrier group and different mags that are unique to the caliber. If it is your first build, stick with basics and do .223/5.56 build to understand more about the weapon and how they work.

[acj415]

First build... so it's best to stick to. 223/5.56 to understand it more. Got it thanks Centaine. Someone had said that one is better than the other...I think they said 5.56 barrel can shoot. 223 without a problem or something a long that line.

[hydralover]

5.56 can shoot .223 no problem, but not the other way around.

[acj415]

5.56 can shoot .223 no problem, but not the other way around.

Thanks wanna make sure to understand before I get started getting parts

[xfer42]

You can shoot 5.56 out of .223 Wylde just fine.

[T.Yoon]

5.56 NATO shoots 5.56 NATO and .223 Remington.

.223 Remington only shoots .223 Remington.

.223 Wylde shoots .223 Remington and 5.56 NATO.

[wpage]

They are the same...

[Billy88]

They are the same size but different loads.

[Billy88]

acj, if you hve any questions about building your AR, feel free to ask me. Its a hobby of mine.

[6114DAVE]

acj, if you hve any questions about building your AR, feel free to ask me. Its a hobby of mine.

Billy!! Let's see a pic of your build buddy . You EASing soon?'

[kcstott]

They are the same size but different loads.

Incorrect.

It not the load per say that is the issue. you can buy .223 that is loaded just as hot as the NATO stuff.

NATO depending on how they test the rounds are 55,KPSI to 62,KPSI
the .223 Rem is listed at a saami pressure of 55,KPSI and a CIP pressure of 62,KPSI so tell me how it's different loads again??

The issue is the chamber the longer throat of the NATO chamber gives more freebore and therefore a lower pressure reading initially which is also why they changed the way the test the loads.

As long as you are shooting this in a modern 5.56 chamber rifle you will have no issues. If you have and old Steven's savage break action from the fifties then yes I'd use .223 rem only in it. If it's a Rem 700 in .223 I'd have no issue shooting NATO ammo in it at all.

[wpage]

Thanks KC for clarity...

[bohoki]

the 762x39 is a caliber conversion for a standard ar-15 so you mill your blank to ar-15 specifications