I was just speculating, as I need a really light rifle. I wonder how light a 9mm Colt AR could be made?

What got me to thinking about this was the Olympic Arms 5lb FAR .223.  The barrel is real skinny, I think.

Anyway, I held the barrel of one of my 9mm pistols, up to my AR 9mm and noticed the AR barrel was somewhat thicker.  I suspect it is considerably thicker under the handguards (but have not removed them to check).

Once I get my 9mm AR fully loaded, it seems pretty heavy to me.

What do you guys think the chances are of making the barrel skinner on my 9mm AR, and getting it down to 5 pounds unloaded?  It is 7 pounds unloaded now.

Best,
Zippy

The preban 9mm colt I just got is real light.
I don't know which model you have but mine is the
lightweight sporter, the barrel is pretty thin. Put a tele-stock on it and cut your weight even more.
I don't see how much lighter it can get other that getting a 10.5" barrel with a 5.5" flash suppressor.

I am not an expert by any means but I have just completed a lightweight .223. I used a Hesse Aramid upper and lower,which saved about 3.5 ounces over the aluminum. I used a m-4 style barrel and it came out to 5lbs 6 oz with a ARMS 40 folding rear sight. I wouldassume you could lighten a 9mm barrel because of the lower pressures involved but unless you lighten the receivers somehow I doubt you could get it down to 5 lbs. Not to mention the receiver block that you need for the 9mm magazines, I don't know what that weighs but I would guess about 3 or 4 ounces.

BTW for those of you out there that are getting ready to comment on the Hesse receivers, these have worked flawlessly so far. I have only one complaint, the hole for the bolt catch spring had a burr in it but it was easy to clean it out with a drill bit. Only time will tell how it holds up.

You should look into Cavalry Arms. Once full-auto.com comes back up you can look into the group buy on lightweight guns. the plastic lower and light barrel make them really light. If 10+ people buy, the rifles are $600.

Keep talking.  I'm listening...

Zippy

Even though I own a OLY/Cav-arms 9mm rifle,  they are not necessarily any lighter than a .223 model, regardless the size of the cartridge.

3 reasons:

*  The Oly upper has a heavy barrel to accommodate the larger diameter cartridge.

*  The bolt carrier is quite heavy compared to a .223 bolt. It is made for the blowback-style operation of this upper.

*  Sten mags are STEEL.  which are sturdy but far from light.  Plus, if you load it up with 32 rounds of 9mm, it gets even heavier still.

If you really want to lighten up one of these rigs,  stick with the Cav-arms lower and send the upper off to KKF to have the barrel turned down to a skinnier profile.  There have been recent posts here on how to cut back your Sten mags to a shorter (lighter) length.  Another route you can go is to have Oly modify your upper to accept Glock mags, which are about as light (though expensive) as they come.

Drop your weight by adding an ACE ARFX skeletonized stock for about $100.

You could cut the barrel down. SBR.

I think I am going to get me a CAV15: www.ar15.com/forums/topic.html?b=2&f=61&t=138385&w=myTopicPop

If you have the Oly 9mm all your weight is in the barrel because it's an HBAR(?). That bugged me too, a 9mm should be light weight.

I had one machined down to .75 inches under the hand guards. The smith said he could take it down to handgun barrel thickness but I thought that would be going overboard. .75 under the guard is roughly .2 inch thick barrel. Thats not much steel for such a long barrel.

If the Oly 9mm was gas operated then the bolt carrier would be a lot lighter, but thats the draw back to blowback operation.  The thing is just gonna be heavy.

The 9mm Colt is light.

You could take the barrel down to .625/650. Uzi barrel is .625 for most of it's length. Problem with AR is if you lay the front on sand bag, then you flex barrel (sorta similar situation that  the float tube remedies).

This is interesting.

I agree with BoomStick.  A 9mm should be light, like around 5 pounds max.

The 16 inch Colt, with standard stock is listed at 7 and 1/4th pounds.  The same .223 version is 6 and 1/4th pounds.

Zippy

This is interesting.

I agree with BoomStick.  A 9mm should be light, like around 5 pounds max.

The 16 inch Colt, with standard stock is listed at 7 and 1/4th pounds.  The same .223 version is 6 and 1/4th pounds.

Zippy

Quoted: The 16 inch Colt, with standard stock is listed at 7 and 1/4th pounds.  The same .223 version is 6 and 1/4th pounds. Zippy

I'll bet that extra pound is in the bolt and magazine block.