So I thought it would be fun to build my own AR. I chose to build it in 204 Ruger. Watched the video clips and read as much as I could so I had a good idea of what I was embarking on.

So I purchased all the parts I needed and went to assemble. This was to be a gun for my wife as a Christmas gift in 2011.

The problem I ran into is that I could not find a barrel nut made for a bull barrel, So i purchased a standard one and reamed it out to fit. Knowing that this is the part that holds the barrel on the firearm I commenced to make sure it slid over the barrel easily, but with as little clearance as possible to maintain as much "grip" as I could.

So I put the barrel on and use some of this C5-A stuff on the threads and commenced to torquing the barrel nut on. When I was at 30 ft-lbs the notch closes lining up the gas tube was just past, so I knocked the wrench up to 40 and tried again. The nut did not move a whole lot. so I went up to 50 etc. At 60 I felt that was probably way high enough and I could tell that I was not going to make it to the next notch for the gas tube at 80 ft-lbs, if ever. So I figured I would take it all apart again and do some more research, figured maybe the C5-A was probably a bad choice.

Upon backing off the barren nut it became quite hard to turn, I was afraid that I somehow cross threaded the nut and became concerned that I screwed up nut I worked so hard to ream out (that shit is some hard metal!). So I tighten it back down a little to make sure it is not cross threaded and try to take it off again. Same hangup so I thought: 'well, i can't screw it up much more than I already did" and gave it some more juice. I hear a crack and was concerned so I stopped to see what happened. I found a small crack that started up the upper receiver from the threaded portion. That made me think "Now I really cant break anything else, but I gotta get it apart yet to save the barrel" so I gave it more as I listened to the nut and the upper grind together, very bad sound. Finally I hear a louder 'Snap' that I later learned to be the Index Pin shearing off of the Barrel. Once I had the barrel nut separated from the upper I removed the barrel and learned that I had broken about everything but the nut. So I beat the barrel nut off of the barrel, scratching the shit out of the nice stainless steel half the way. The barrel is marked to shit where the barrel nut was catching on the barrel and attempting to turn the barrel thus cracking the upper receiver and shearing the index pin. Expensive lesson learned, ream the nut out a bit more.

So after that I was sick to my stomach and put it all in the basement until I could look at it again! In the mean time the wife decided she could not adjust to living with another person and she was the most important thing in the world. I let her have her divorce and am sitting back to watch the shit show that will become her life.... but anyway. I had examined the barrel and it appeared to me that the index pin was not machined on the barrel and it looked like it could be replaced (I was rather surprised that I could shear Stainless Steel anyway if that were not the case). So I started investigating my options. I found this place ADCO that would replace the pin, I am expecting the barrel to be back towards the end of this week. I plan to purchase another upper today so i have all the parts and can maybe try assembly again this weekend....

So, long story and thanks for hanging in there, my plan is to ream the barrel nut out some more as to allow more clearance so it does not catch on the barrel itself. I am unsure yet of what I will use for grease on the nut. The real question is, what if I get the nut back on and run into the same problem? 30 ft-lbs is just past one notch for the gas tube and 70 ft-lbs won't get me to the next one?

Any other tips and pointers would be greatly appreciated also!

Thank You.

Divorce and gun problems, all in one.  Damn. Sorry bout the AR.  No help here, never put a bull bbl on.  Usually end up torqueing mine to 40 lbs.  Somebody has to be selling the correct nut.

Contact ADCO and have them put an upper on the barrel before it leaves their shop.

With the problems you've had, I would send the rest of the upper parts to ADCO and let them assemble the upper.

Check with ADCO or WOA to see about your barrel nut. As for the divorce I have nothing to offer. Keep moving forward!!!!

Maybe that receiver lapping tool midway sells. http://www.midwayusa.com/product/810457/ar-stoner-upper-receiver-lapping-tool-ar-15. If you remove small amount at a time. Should allow you to get tube slot aligned.

Great Idea!

Problem is they just shipped it back to me yesterday, that is what spurred me to look for an upper (which seem about impossible to find in stock it appears) and post this!

I find this process quite entertaining and fun, so I don't mind... just have to think a bit more ahead it appears!

Kit,

What hand guard are you putting on this rifle?

it may time better with the different upper.
if you are having trouble timing it you tighten loosen a few times, try a different barrel nut, lap the receiver.

Purchased a Magpul MOE - using a Troy Low Profile Gas Block.
Purchased a used DPMS barrel on GunBroker - So I knew it was a decent shooter...





Interesting.... never thought about lapping it...
Thanks!

ADCO has uppers in stock....send it back.

Should find the correct barrel nut for the job first.  Not make a barrel nut fit.  

Molly greese on the threads, tighten the nut, losen the nut, repeat at least three times before you start torquing things.  

I would also second the advice about sending it to ADCO to mount on an upper.  Expensive mistakes tend to get more expensive unless you learn the correct lesson.  The correct lesson here IMHO is use the right part for the job and not make a part that you "think" will work.

I could not find a manufacture of a barrel nut for Bull Barrels. From the Forums I understood that it was common practice to just ream one out....

I'm not an expert in reaming out barrel nuts.  Hence my IMHO.  I would think where ever you got your barrel from should have the correct nut to go with it.  You might be correct though.  However, I can promise you that ADCO will do it right and you won't have to worry about it.  Might be cheaper than trying again.

Just my $0.02

It's a lot of work to have a 1.000 (or even slightly larger) barrel instead of a 0.980 one.  Somehow I doubt that there would be any performance difference to justify it.  For the reduction in grief factor alone I'd have had ADCO turn it down to .980 or slightly smaller while they had it there.  Then get two or three barrel nuts (they aren't expensive), get the correct spec moly grease, and put on your barrel.

I agree. I kind of wanted a standard size barrel, but it appears that in 204 Ruger you can only get a Bull Barrel...

It seems I should have built a different caliber first then did one with the different stuff!

+1





 

If you're describing exactly what you did, you didn't follow the proper procedure for barrel installation, which is to:

1) lube
2) torque to 30 ft-lbs and back it off again
3) torque again to 30 ft-lbs and back it off again
4) torque again to 30 ft-lbs and back it off again
5) torque to 30 ft-lbs, see where your notch is, and go up to 80 ft-lbs to line up the notch, if necessary.

2-4 are very important to settle the threads in to each other before going for a final fit.

If that doesn't work, you can face and hone the front of the receiver in very small increments to change where the notch lines up.

I don't understand the problem you describe at all.  You shouldn't have to "reem" anything.

DPMS bull barrels are .920" in diameter.  They are not bigger in diameter than the barrel extension, nor the "lip" between the barrel extension and the barrel proper.

Barrel nuts thread on to the upper, which is larger in diameter than the barrel.  There is no special "bull barrel" barrel nut.  Did you reem it so you could slip it over the gasblock without removing it?  If so this is indicative of a larger problem and you need to re-watch your videos.

- AG

The first half of the barrel, between the gas block and the receiver is 0.936... I can not find a barrel nut that is any bigger than 0.92. Hence, 0.016+ has to be reemed out to fit it over the larger part of the barrel.

This is the barrel at Brownells

Eta: I either did not pay enough attention enough to see that it should be torqued three time, or I was lost in the excitement of the last step of my first build and forgot!  Thanks for pointing that out to me.

That's the source of your difficulties.  .936 is the gas block journal, not the barrel diameter under the barrel nut.

I was unsure as the barrel is in transit and it has been 5+ months since I measured things. All I can remember for sure is I slid the barrel nut down the barrel and it didn't go the whole way. it got stuck where the gas block went. Knew something had to get bigger or something else had to get smaller...

I have seen shims available for situations like this and/or the receiver can be faced/squared/trued to make slight adjustments.

Just an update,

Got all the parts Friday. Borrowed a finger of moly grease from work and went to building. Watched the video on Brownells about installing the barrel again, which does not mention torquing and backing off BTW.
This time the build went off without a hitch no doubt due to what I had learned from the first attempt and the advice in this thread. Thank You.
During my extended reading this time around I was reading about how important it was to check head space. I was in the big city Saturday morning so I swing by the local place and had them check what they could. They only had a Go gage in 204 Ruger, but it seemed to close a little tight on that so figured it was GTG. So when I got back home I ran out and fired a round to check the brass. Everything looked find on it.

So here's the pic, my apologies for only including part of my feet and for wearing socks.




I have yet to choose an optic.

looks terrible start over

Bare feet would have been better.

Looks good though !

Looks good (and hugely long), glad everything worked out in the end.

BTW, not enough feet, let's correct this for next time!

I edited the image on my phone after I took the picture... just to get my feet outta there. Apparently I was not accurate enough!

She is a tad front heavy.. more so than I thought it would be. Might end up with a Bipod on it someday...

I have a 24" WOA .204 Ruger barrel on a AR that I built.  With a Magpul PRS stock it is balanced but heavy.  I know I wont be packing it around the woods.  Maybe 15 yards from the Jeep when I go shooting.  Looks good.  Buy some factory ammo and see what Grain bullet does well before you start reloading.  I bought 40gr bullets and my barrel like 32gr bullets.  

MAHA

Never thought about it... I purchased some 40 Gr Hornady, but it is hard to tell anything without some sort of way to aim!

They guy I purchased the barrel from sent dies, brass and a few boxes of 32gr bullets. I suppose that ought to tell me something right there huh!