Hi all,

I had a fun time with this project.  I wanted to make a second attempt at building a very light-weight AR15.  At the same time, I have a friend that I have enticed into the cult of the Evil Black Rifle, and I set this project up as a build-it-yourself class.  Thought I'd document what it looks like for anyone that wanders by the BIY forum.

What's cool about this project is that I held-off assembling any parts until today.  So the entire project from parts to rifle was about 2 1/2 hours, including problems and finishing touches.

At 10:00am this morning it looked like this:



Tools ready in the kitchen for building the lower:



Here's the garage workbench ready to assemble the upper:



We're off!  Eagle Arms lower gets a trigger guard and magazine catch:



Had some trouble with the roll pin for the bolt catch.  I think I should have wiped it with oil before I began, because it didn't want to go the last .001".  Got it in and flush but not without losing the blueing on the pin, which fixed-up with cold blue later.

Also ran into a very strange problem with the pivot detent spring hole.  It was drilled too deep.  I had to cut a tiny length of coat hanger wire and drop it in the hole to bring the spring and detent up to where adequate pressure was put on the pivot pin.  Very wierd, but it worked fine:



Smoothed the sear surface of the trigger with 400 grit emery before installation.  Trigger went in, though it took forever to get the pin to line-up with the disconnector:



Polished the hammer, installed no problem:



Ace Ultralight stock finished off the lower, piece of cake:



Function tested the lower, everything works great.  Now on to the upper.

I chose a Vulcan Arms carbon/Aramid flat-top upper receiver because it's extremely light and looks cool with no forward assist or ejection port cover.  Also very cheap.  But in test assembling it the day before I found the fit to the Bushmaster superlight barrel was loose.  I cut a wrap-around shim (soda can aluminum) to go on the barrel extension, full width from the shoulder to the edge near the lugs, and completely enclosing the barrel extension.  I also had to make a micro-tiny shim to wrap the index pin.  Now it's snug:



Delta ring, weld spring, snap ring, and a 3/16" rod to keep the gaps lined-up:



I went easy on the barrel nut, because I really don't know what to expect from the carbon/Aramid and I'm paranoid that I could strip it if I honked on the wrench.  I will need to watch this when I test fire it.  Gas tube lined-up, tested with the bolt, nice and centered.  Gas tube pin went in very quickly:



Almost done!  Topped the receiver with an ARMS #38 standard-length Swan sleeve.  I was going to do just a #40 back-up sight, but in trying the flattop with the OKO, the red dot was in the middle of the front sight pin.  I found this distracting.  The #38 rail gets the red dot up above the pin:



OKO goes on top and we're done.  I don't have an accurate low-weight scale, so I did the hold-it-put-it-down-a-few-times method with the bathroom scale and I think its a little under 5 pounds.  Here's the finished product:





Now that wasn't hard, was it?  

Specs:

• Eagle Arms stripped lower (Quantico)
• Vulcan Arms Carbon/Aramid stripped flattop upper (Vulcan Arms)
• Rock River Arms lower parts kit and charge handle (Georgia Precision)
• Rock River Arms bolt, bolt carrier (Eagle Firearms)
• Ace Ultralight stock (Del-Ton)
• Bushmaster superlight 16" post-ban barrel kit (Eagle Firearms)
• ARMS #38 standard-length Swan sleeve (Eagle Firearms)
• OKO red dot sight (Brownell's)

C_M

RANGE REPORT

I finally made it out to the range.  It was a great day, nice weather, and I had DPRC to myself.  I shoot on the 50 yard range because I'm too lazy to walk far.

I fired 100 rounds of Lake City (Federal) 55gr. and 100 rounds Wolf 62 gr.  Used four different 30-rd USGI and one 20-rd USGI.  The Lake city was fired first for sighting-in, then the Wolf for rapid fire (thirty followed by twenty).

Results: No failures to feed or eject, no jams of any kind, last round bolt-hold-open worked every time!  100% functional in every respect.

This rifle ROCKS!  My kids would say SHWEET!  It handles like a baton, has good accuracy and is a blast to shoot.

I did a careful cleaning afterward and find no indication that the Vulcan Carbon/Aramid upper will have any problems.  I ran the carbine up hot so that smoke was pouring up around the FSB, but it didn't seem to bother it.  What's better, the upper proved extremely easy to clean, all the grit wiped off with a shop rag, and it looked like new on the inside (except around the gas tube, of course.)

The sights worked GREAT.  The OKO sight is up in the clear, about 1/2 inch higher than normal.  When the dot is centered in the sight its about 1/4" above the sight pin.  And the ARMS sight worked great.  If I was going to be a purist (like Tyrod ) I could have done the gas block thing and ditched the ARMS #38 and shaved off some ounces, but I like having both the red dot and the iron sights.

Only two odd things about the rifle: the rear sight is about 1 mark to the right of center, and it drops brass about 5 o'clock behind me.  Hardly worth mentioning.

C_M

OMG! springs and pins on a dinner plate......you rock! I'd get run out of the house.

Looks real nice.

What you should have asked is: "How come you got an extra pin and spring in the last pic of the lower?"  [:D]

Close-up of the right side, just because I'm attention-deprived and entirely too proud and self-centered:

[img]http://home.mebtel.net/~hicksfam/build/s-light_detail.jpg[/img]

Dude, this thread rocks.  I wish I had the patience like you and took a pic of all of my new parts (except for pre-ban lower that I completely stripped of parts and cleaned up).  Oh well, live and learn.  Did you headspace your bolt and barrel?  

Edited (in response to Stickman's post) to say: Did you or will you check the headspace of the bolt and barrel combination with a set of headspace gauges?

Further edited for pic of my new Lightweight build
[img]http://www.hunt101.com/img/121148.JPG[/img].  

p.s. dude, your pictures are really nice.  It seems my picture taking skills needs work.  

I enjoyed the pics.  I also have a Hesse Carbon/Armid upper unit.  I was wondering you, Carbine_Man, or anyone else had experience with a Hesse Carbon/Armid LOWER.  Will it hold up?  Which has more stress the upper or the lower?

You can't headspace your AR15, it is either there, or it isn't.  

No, I just put it together.  I didn't headspace my first or second home-built either, and I've never had any indication of headspace problems.  The odds of getting a bad headspace are pretty small, because of the way the barrel extension works.

Did you build your own upper?  If so, how hard did you tighten the barrel nut?

I have no experience with the Vulcan lower.  However, I would be concerned with the "ears" where the pivot pin holes go.  Those bumps just poke out there unsupported.  

Its may be true that for the same weight the carbon/Aramid may be as strong as or stronger than aluminum.  My question is, for the same thickness or amount of material, is it as strong as aluminum?

The upper is a different story.  The bumps in the upper where the pivot and takedown pins go are thick.  And the barrel nut and extension spread the stress of the barrel over a large area.  I'm no engineer (could be way off) but I think the upper doesn't have to be as strong as the lower, especially at the pivot pin holes.

That said, the Vulcan upper flexes, and I wouldn't try to build a target gun from one.

I can't wait to torture-test the upper and see how it holds up.  I too would like to hear if anyone has had experience with the Vulcan lower.

Nice job Dood.  I have a similar setup with barrel and upper.  I didn't have any issues with looseness.  Wonder if it's the barrel or upper.  I should have the Vulcan lower by monday. So I'll report back then about my impressions.  Oh that's right, I don't do impressions.  My evaluation then.

Excellent!!!

Informative and succinct!!!

Carry On!

Great job on the build.  The rifle looks awesome!  Let us know how it shoots.

Just kind of curious to know what kind of prices you guys are paying for these carbon uppers and lowers. They list them at 80.00 on the site, but one guy posted in a diff. thread that they only billed him for 46.00 for a upper. I may go with this upper on one of my next builds.


Viper out....

The [i]"one guy"[/i] may have been me.  I didn't ask for any special discount, but it looks like they charged me a dealer price.  $48 or so IIRC.

C_M

GREAT POST and writeup!

Please do tell us where you got the parts and how much.

Also, please post range report!  Must have read a dozen build reports that end with "I'll post a range report next week"

NESurvival,

I put the supplier of the parts next to each part at the bottom of the post.  Prices were as Web-published by each supplier, except for the Vulcan upper which was ~$50.  

Eagle Firearms does about 5-10% better on prices they quote vs. the mfg. prices (ARMS, for instance.)  In fact, I should say "Thanks, Chris @Eagle Firearms for your patience when I changed the order twice."  They were very accommodating and got my special-order barrel kit to me promptly.

Range report will be posted.

I do will post pics in a new post as not to hijack this one :D Carbine_Man yours looks great good luck.

I'm not sure I like your upper, but excellent post and good job, kinda makes me want to build another.[:D]

Back to top.

Maybe I shoujld have written something about how that Vulcan upper blew-up in my face.

Never mind.

C_M

Actually, the BM FSB is a couple of grams lighter than the one I have.

Any word on group sizes?

I spent 8 hrs on the milling machine today and managed to get rid of a whopping 21 grams.  Oh well, it's gonna take some time.

As to group sizes, anything smaller than full choke 20ga, is okay by me.  [;)]  Seriously, I don't shoot well enough to be a judge.  With the red dot I can keep 5 shots on a 50 cent piece at 50 yards without trying too hard, and for a CQB setup, I'm okay with that.  My 47-year-old eyes, ya know?  I'd have to scope it to do better.

I keep looking at your gun and thinking how I could swap out the lower for a Vulcan, but I'm happy with the way it turned out.  Besides, the lighter the gun the more the perceived recoil (not that 5.56 is harsh.)  Life is full of compromises, and this gun suits me.

Keep going for the light-weight trophy [b]Tyrod[/b].  Keep us posted on what you've got it down to.

I built mine with a Hesse (now Vulcan) kevlar lower that is jet black, ACE skeleton stock (I want the ultra light stock now), Vulcan upper and a Model 1 ultra light barrel with aluminum flat top gas block and a cav-comp, standard CAR handguards and A2 pistol grip.

I havent grouped it yet but like any AR should have more than reasonable accuracy, it is set up with an ARMS #40, flip up front sight of unknown origin and a Bushnell Holo Site (because it does the same thing as an Eotech and I got it for $100).

The lower has been around a while and has several thousand rounds on it, no evidence of wear or damage (also probably 10,000 dry firings between myself and my boys). I played with theis lower on a 24" DPMS side charging bull upper, SP1 upper, A2 upper, 16" Hbar flat top and now the ultra light. It started life as a Hesse 9mm carbine, the original owner kept the upper and mag block, so this one has been around and has more than amply stood the test of time (at least in my opinion). THe color of course doesnt match the Vulcan upper but there current lowers are the same swirl gray as the uppers and would match nicely. Dont hesitate, I have not read one shred of negative press about these lowers only one Hesse aluminum lower that broke off at the rear (remember the story? looked like the carrier key whacked the recoil tube ring). Anyway, I love mine (as my wife call all my guns "my girlfriend", that means I have my own harem!).

Jeff

Carbine Man,

Thanks for taking the time to write this.  You did a great job.  

I know anything Vulcan catches a lot of crap, but everything I've read about their Carbon fiber upper and lower has been positive.  

I passed on a lower at a gunshow a while back, but I may pick one up if the guy is there at the next one.  I've been considering using them in conjunction with a Bushy pencil barrel and keeping the overall weight to an absolute minimum.


Jim

Carbine_man:

I didn't torque it so I don't know the exact measurement.  I was worried about stripping it so I just tightened it gently until it didn't give easily.  Then I turned it back slightly so the gas tube would fit.  It's not loose and it didn't stip the threads.

[b]fq1234[/b]

Sounds like what I did.   I just wrenched it until it seemed firm and lined up.

I have no idea whether the barrel nut could come loose or how it could come loose.  It seems to me that the gas tube fits so snug in the barrel nut notch that it can't really "wiggle" loose.

Would the barrel nut back off and cause the gas tube to bend?

Guess I'll just have to watch it.

C_M

That doesen't seem very likely to me.