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Notblake
06-19-2010, 10:09 PM
Was thinking on my last backpacking trip, I wonder how light we could make a ar15?

So AR gurus, With a 14.5 pinned or 16 in straight Pencil profile barrel, no optic, no quad rail, no fancy 6 way stock (or a ultralight adj stock) a no nonsense ultralight AR. How low could we go? The idea of a featherweight .223 is very apealing to me for extended stay backpacking / shtf.

Plisk
06-19-2010, 10:14 PM
If you truly want to get the lightest possible, I've thought this through quite a bit.

-Cavalry Arms Lower
-14.5" Pinned Pencil Barrel
-Troy TRX Extreme rail (I'm not 100% sure, but I believe the Troy Rail with a Troy front sight is lighter then the delta ring assembly with A-frame)
-Aluminum BCG (I can't remember the companies name, but they made a few in different materials a while ago)
-Surefire or KAC break

Done. You could easily get under 5 lbs with this set-up.

Notblake
06-19-2010, 10:20 PM
If you truly want to get the lightest possible, I've thought this through quite a bit.

-Cavalry Arms Lower
-14.5" Pinned Pencil Barrel
-Troy TRX Extreme rail (I'm not 100% sure, but I believe the Troy Rail with a Troy front sight is lighter then the delta ring assembly with A-frame)
-Aluminum BCG (I can't remember the companies name, but they made a few in different materials a while ago)
-Surefire or KAC break

Done. You could easily get under 5 lbs with this set-up.

Do you think that the ALU BCG would be worth the loss in svc life?

bjl333
06-19-2010, 10:40 PM
If you truly want to get the lightest possible, I've thought this through quite a bit.

-Cavalry Arms Lower
-14.5" Pinned Pencil Barrel
-Troy TRX Extreme rail (I'm not 100% sure, but I believe the Troy Rail with a Troy front sight is lighter then the delta ring assembly with A-frame)
-Aluminum BCG (I can't remember the companies name, but they made a few in different materials a while ago)
-Surefire or KAC break

Done. You could easily get under 5 lbs with this set-up.


I would go with a Plumcrazy complete lower. They are complete polymer lowers.
The upper I was thinking about the same as you, since the Carbon 15 upper uses a different BCG is what I heard, so thats out ...
The Plumcrazy's reliability is unknown to me. But I bought one to start what we're talking about here. I am not gonna put thousands of rounds thru this gun, so as long as I can get good reliability on my first sight in session of 2-300 rds I'll be happy !!!

bjl333
06-19-2010, 10:43 PM
PS ... I got the Plumcrazy lower at T & A Armory in Santa Ana, CA. It cost $150 + tax + DROS = $189 I think.

1988
06-19-2010, 11:04 PM
If you think of polymer on AR15, you should take a look at the SU-16CA.

bjl333
06-19-2010, 11:09 PM
If you think of polymer on AR15, you should take a look at the SU-16CA.



Have one !!

Want an AR platform ...

Plisk
06-19-2010, 11:16 PM
Do you think that the ALU BCG would be worth the loss in svc life?

I've never heard of a bolt carrier wearing out. They were just aluminum carriers, the bolt itself is standard steel.

bjl333
06-19-2010, 11:18 PM
I've never heard of a bolt carrier wearing out. They were just aluminum carriers, the bolt itself is standard steel.



Do you know where to find one ??? BC ...

Plisk
06-19-2010, 11:35 PM
Not many of them were made, I've seen them but never one for sale.

I'm trying to track down the company name.

Plisk
06-19-2010, 11:45 PM
JP rifles made them a while back in aluminum, titanium and a few other materials. I don't see any new aluminum ones on their site now, but with google-fu you might find an old one.

http://www.jprifles.com/1.4.7_bc.php

1911su16b870
06-19-2010, 11:51 PM
The Bushmaster Carbon 15 is a tad heavier than a SU16...IMO the Carbon 15 is the lightest stock AR platform rig.

1911su16b870
06-19-2010, 11:54 PM
JP rifles made them a while back in aluminum, titanium and a few other materials. I don't see any new aluminum ones on their site now, but with google-fu you might find an old one.

http://www.jprifles.com/1.4.7_bc.php

I just built up a JP LMOS upper on a dpms slick side and can state that it is super smooth and sweet...you need the JP gas block with flow adjustment, the LMOS bolt carrier and light weight buffer for the system. Finish with your choice of barrel/handguard and lower/trigger and you are good to go. Still the overall build is heavier than the Carbon 15.

bjl333
06-19-2010, 11:55 PM
JP rifles made them a while back in aluminum, titanium and a few other materials. I don't see any new aluminum ones on their site now, but with google-fu you might find an old one.

http://www.jprifles.com/1.4.7_bc.php



Thanks, will look into !!!

bjl333
06-20-2010, 12:01 AM
The Bushmaster Carbon 15 is a tad heavier than a SU16...IMO the Carbon 15 is the lightest stock AR platform rig.



The Plumcrazy lower is lighter then a Carbon 15 lower.

I am just trying to get an upper together thats lighter then the Carbon 15 or any other upper.

Like I said earlier. I am not looking for 10K round longivity, just the lightest CA legal AR rifle I could build !! Part of the fun is putting it together the way your mind pictured it ...

Al LaVodka
06-20-2010, 6:29 PM
The Colt Target Lightweight (.223, 16" 1:7 pencil barrel w/out Muzzle or Lug) weighed 6.7 lbs. with a full length stock. Put a telescoping stock on such and it's gotta be about the most perfectly balanced 6 lbs. it has ever been my pleasure to hold. The kind that gives ya a dopey smile.

Now there's a fixed stock the length of a closed telestock -- about 7" vs. up to 10".

Al

C_1
06-20-2010, 7:28 PM
I have actually thought about a light weight AR as well. But Im not too fond of the Carbon15, Calvary Arms or Plum Crazy lowers.

It wouldnt be the lightest but I'd just go with a standard AR lower, ACE fixed stock, MMG, A2 upper with carry handle sight, 14.5" pencil barrel with pinned/welded muzzle brake, fixed front sight gas block, and standard handguards. Simple and lightweight (enough). Featureless with a MMG allows detachable mags :)

pyromensch
06-20-2010, 9:46 PM
i believe that the weight of the weapon is dependent upon how much ammo the you are going to carry.

UserM4
06-20-2010, 9:57 PM
I'm pretty conscious about weight and I even went as far as replacing small parts that I've found lighter counterparts with. But I also have real world expectations and durability of the rifle. I think an average AR15 without accessories and ammo are gonna be around 6.5-7.0lbs. Maybe lighter with plastic handguards. I wonder how some people with 16" M4 profile barrels are getting in the 5lb range.

Plisk
06-20-2010, 9:57 PM
i believe that the weight of the weapon is dependent upon how much ammo the you are going to carry.

Not really. A light rifle can be carried with 2 mags or 12.

ArkinDomino
06-20-2010, 10:05 PM
A pencil profile barrel in combination with a MOE hand guard and a CTR will make the rifle as light as it needs to be. I don't see the benefit to those polymer lowers as they don't seem to be much lighter to make them worth the trouble/risk. Doesn't most of the weight on ARs come from heavy barrels and rails?

bjl333
06-20-2010, 10:39 PM
The topic was how light the AR's could be.

My take is the lightest possible build. The Plumcrazy is the lightest lower assembly out there. I said earlier I wasn't looking for 10k rds duribility, thats why the subject of an alumium bolt carrier came up as well.

I compare this to building a max horsepower engine. It may not last to 100k miles, but it'll sure be fun driving it. I just wanna build the lightest platform I could dream up !!!

ar15barrels
06-21-2010, 1:24 AM
JP rifles made them a while back in aluminum, titanium and a few other materials. I don't see any new aluminum ones on their site now, but with google-fu you might find an old one.

http://www.jprifles.com/1.4.7_bc.php

JP quit making them out of aluminum because of short service life.
John Paul told me they would last about 2000 rounds before the area where the tail of the bolt would get eroded oversized by the gas and the gun would start to short stroke.

bjl333
06-21-2010, 1:29 AM
JP quit making them out of aluminum because of short service life.
John Paul told me they would last about 2000 rounds before the area where the tail of the bolt would get eroded oversized by the gas and the gun would start to short stroke.



Thanks Randall, I'll be looking into their low mass bc ...

yasushi
06-21-2010, 7:05 AM
The lightest build I got was a 4 1/4 pounds on the Cavary MKII lower on the BM Carbon 22 upper. The complete MKII lower with buffer/spring is almost 2 pounds.

Forestgnome
06-21-2010, 7:09 AM
These guys carry titanium bcg's.

http://www.gunaccessories.com/AR15-M16Parts/BoltCarriers_Assemblies.asp

ar15barrels
06-21-2010, 8:17 AM
These guys carry titanium bcg's.

http://www.gunaccessories.com/AR15-M16Parts/BoltCarriers_Assemblies.asp

That's just titanium nitride coating over regular steel parts.
That's NOT made of titanium.

1911su16b870
06-21-2010, 10:31 AM
The Plumcrazy lower is lighter then a Carbon 15 lower.

I am just trying to get an upper together thats lighter then the Carbon 15 or any other upper.

Like I said earlier. I am not looking for 10K round longivity, just the lightest CA legal AR rifle I could build !! Part of the fun is putting it together the way your mind pictured it ...

I would go a Clark carbon fiber handguard shortened to carbine length over a lightweight barrel with A2 front sight and A3 carbon 15 upper receiver with magpul plastic BUS. That should be the lowest weight upper you could make IMO.

BTW how heavy is the plumcrazy compared to the carbon15?

Exile Machine
06-21-2010, 10:31 AM
+1 on Cav Arms. Get one while you can. If you go with a stripped lower instead of Cav Arms, for a lightweight fixed stock look at the ACE ultralight entry AR-UL-E stock (http://riflestocks.com/catalog/product_info.php?cPath=75_77&products_id=193) @ 5oz.

bwiese
06-21-2010, 10:44 AM
My concern would be that if you're "not aiming for 10K rounds reliability" you could well end up "not even targeting ~1500 rounds reliability".

freonr22
06-21-2010, 10:52 AM
Just build an ar pistol?

Californio
06-21-2010, 11:13 AM
I did this drill 30 years ago. Flame suit on. Using and external frame, 45 pound pack and placing the rifle sling over one side the best rifle is a Mini-14 with 5 five round magazine for a flush fit. An Ar15 even with no magazine has the pistol grip and mag well that gets in your way with a full pack, when slung. Note only 20 rounds AR magazines in those days.

If you want a quickly retrieved SA rifle that does not bother you, Mini-14 is the solution. Cutting down the barrel to 16.5 like CRT Guns does or the NRA model works even better. The Mini is straight across the bottom and contours to the side of the pack. Sewing on a velcro wrap to the pack will hold the rifle butt to the pack as well. I carried a 20 rounder in those days for backup.

It was purely an ergonomic decision, AR is the better rifle.

Forestgnome
06-21-2010, 9:21 PM
That's just titanium nitride coating over regular steel parts.
That's NOT made of titanium.
Seemed pretty cheap for titanium. Well that's bogus, I want solid titanium! Really, the only places you're going to save weight that you can feel would be in the steel parts. The bcg and the barrel are the only options there. I guess you need to save at least 2 oz in a shot to notice the difference.

ar15barrels
06-21-2010, 9:34 PM
Seemed pretty cheap for titanium. Well that's bogus, I want solid titanium! Really, the only places you're going to save weight that you can feel would be in the steel parts. The bcg and the barrel are the only options there. I guess you need to save at least 2 oz in a shot to notice the difference.

The hint was the gold color.
Titanium nitride is usually gold.
Real titanium is gray.
You would not use titanium for the bolt as it's not as shock resistant as properly heat treated steel.
You would not use titanium for the gas key either as it would not handle the heat as well.
A true titanium bolt carrier group would only have a titanium carrier as that's where the weight savings would be significant.
The cost would be VERY significant as well.

bjl333
06-22-2010, 12:27 AM
My concern would be that if you're "not aiming for 10K rounds reliability" you could well end up "not even targeting ~1500 rounds reliability".



Thanks Bill, Its looking like I'll just take one of my existing upper and have Randall take the barrel down to a 14.5 + perm fh feather weight profile. That way I'll have the reliability. I might just go with the lowmass bc and call it a day!!

Now just gotta find the extra change inside the couch and maybe kids piggy bank !!