AR platform question. 223 vs 308 and how are they different?


kayateyellowsnow

kayateyellowsnow

New member
the subject line is rather vague, my real question is this:
I want to build/buy a AR-15 while I can. I used to have a Colt AR-15 but sold it. I would like a .308 instead of the standard 5.56mm. If the 6.whatever mm round was more popular, I'd go that way.

The big question that I have is - are the lowers the same for the .223 as the .308 (yes, I know there is a difference between the 5.56mm and the .223).
I would assume that the magazine would be different as well as the magazine well.

The upper would have to be different too to accommodate the .308, Barrel would of course have to be for the .308, but what about the bolt and bolt carrier, ejector, etc...

If the lowers are the same, would I be able to use the same lower with the 5.56 and just put on a different upper to change to .308??

what would be the best book that I could buy to educate myself for the AR platforms and conversions??
 

The lowers are different, so is the buffer and spring (edit: Sorry, the tube portion is not different, as warbird pointed out).

There are a few "modular" rifles, the most recent being Colt LE901 I believe. The adapter still isn't out for sale, but when it does it will be one of the only rifles that can go from .22 to .308 with just uppers being switched out.

Someone with more knowledge will be able to answer this indepth. I am in the same position as you. The SCAR 17 would be nice, or the SCAR 16...but the price is so outrageous I am looking at other venues for a rifle. If I can get my hands on an LE901 I would get it. Once the adapter came out, and being ambidextrous, I think I would be very happy with it.

Good luck in your venture.
 
The lower is different, it is wider and longer since a 308 won't pass through the mag well on a standard AR lower. The buffer tube is the same, with rifle or carbine length, the spring and buffer need to be a little beefier to handle the additional recoil impulse. The lower parts kit is about 90% the same. The bolt catch and one of the takedown pins are different, the takedown pin is longer and the mag catch uses a screw instead of a roll pin.

There are two styles of 308 ARs, Armalite and DPMS. You cannot use a DPMS upper on an Armalite lower, you can use an Armalite upper on a DPMS lower but you end up with a large gap at the rear of the upper.

If you want to know more details google is your friend, there are websites dedicated to 308 ARs. That is where I found most of what I know. Also my LGS let me set one of their AR10 next to a DPMS style so I could compare the differences up close.

If you have specific questions ask them and if I know I will answer the best I can.

Sent from my SPH-L710 using Tapatalk 2
 
Ok, a trained monkey takes better pictures than I do, but here you go. These show the differences in the overall size of the lowers and the mag well. I have heard about but not seen the conversion model sold by Colt that Chen mentioned, but as I was taking the pictures I realized that I don't understand how the Colt could take a standard 223 upper. The 308 lower is too long. I could see that using a longer (308 length) upper chambered in 223 with the mag well adapter would work. But I don't see how it would be possible to take an upper off of an AR15 and put it on the Colt. Unless the 308 Colt is different from the DPMS/Armalite lower. I have no idea. Would love it if someone had that answer.

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Warbirds said:
Ok, a trained monkey takes better pictures than I do, but here you go. These show the differences in the overall size of the lowers and the mag well. I have heard about but not seen the conversion model sold by Colt that Chen mentioned, but as I was taking the pictures I realized that I don't understand how the Colt could take a standard 223 upper. The 308 lower is too long. I could see that using a longer (308 length) upper chambered in 223 with the mag well adapter would work. But I don't see how it would be possible to take an upper off of an AR15 and put it on the Colt. Unless the 308 Colt is different from the DPMS/Armalite lower. I have no idea. Would love it if someone had that answer.

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Click to expand...

Google/YouTube. There are a few good video's on it...I'm not sure how it works either...but it does. Colt says any mill spec ar upper will fit...

Last time I held the 901 in a store the employee had no idea what "modular" meant, or the capability of that particular rifle...it was pretty sad.
 
Sorry Evosil.... Chen wins this round. Sure enough the Colt 901 is a unique 308 lower that with a very slick conversion block will take a mil spec 5.56 upper. That is almost the best thing since sliced cheese. Since they only sell it as a complete rifle and I can't afford to buy complete, just build, sliced cheese remains king.
 
Warbirds said:
Sorry Evosil.... Chen wins this round. Sure enough the Colt 901 is a unique 308 lower that with a very slick conversion block will take a mil spec 5.56 upper. That is almost the best thing since sliced cheese. Since they only sell it as a complete rifle and I can't afford to buy complete, just build, sliced cheese remains king.
Click to expand...

Doesn't happen often!

If I had the money, I could of picked one of these up a few months ago...now I'm stuck between a rock and a hard place...What to do what to do...
 
Ok.... so I did find one downside. I took an AR upper and tried to fit it on my 308 lower and found one thing. To get this to work not only did colt have to put the angle on the front of the lower, they also had to keep the length of the lower closer to the length of a standard AR15. If you look at pictures of the 901 lower you see that where the buffer tube screws into the lower is in the same place as an AR15 but on a DPMS/Armalite lower it screws in further back. See the picture for clarification on my crappy description, I placed an AR15 lower on top of the 308 lower to show the difference.

Long story short the Colt 901 looks like it will only accept Colt 308 uppers.


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Wait for the insanity to die down and the market to self-correct, since that's what'll happen because the government will not intervene. Trust me, I have an MA in econ and an MBA (not trying to be a bragging ass). I wish I would've picked up an AR-308/AR-10 lower before the panic. Either way I still got a Spike's stripped lower for $135...now they're selling for $550 on GB (I saw an RRA lower for $850 buy it now...holy price gouging!). Now looking for a 6.8mm SPC II upper...talk about a PITA since Stag is backlogged, God knows how far behind RRA is, YHM, Spike's, even DPMS. Some guy on GB is taking pre-orders for DPMS uppers, gimme a break. I refuse to drop over $1k for an upper so that rules out DD, etc. Wait wait wait.
 
It is not an issue of the government "not intervening" it is an issue of them being stopped. They put a ban in place in 94, they have stripped away the rights of gun owners in socialist states and they will do it to all if good Americans don't stand up and stop them.

Sent from my SPH-L710 using Tapatalk 2
 
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