AR frustration

[JonB_in_Glencoe]

Yesterday, I finally started the process of building some cast ammo for AR.
I did some in 2012, back before the sandy Hook incident, but after then, the prices of ARs went crazy, and I sold the rifle.
Last fall, I bought two ARs when the price bottomed out. Both are DPMS, one a Oracle the other a sportical. I had planned on using the Oracle...and this is what this post is about.

I built the first dummy round to find the starting point...OAL for the HM² 225-62-1

No matter what length, the cartridge would stick in the chamber.
I tried a 55gr. J-word, same thing.
I tried a Mil surp round, same thing.
I tried a FL sized empty case, same thing.
Looking into the chamber with the naked eye, all looked OK.

So then, I dug out the Sportical,,, that thing would successfully chamber everything... up to the Dummy round seated to a OAL of 2.215

So I settled with 2.195 (.020") of the lands, crimped with a Lee FCD. So I guess I'll be using the Sportical...and some day, I'll have to dig into that Oracle, and clean the chamber vigorously with a brass brush...as I wasn't set up to do that while all this dummy round assembling was going on.

Anyone have experience with a brand new rifle with a problem chamber?

[imashooter2]

I was just at the range today shooting my LAR-9 and some kids down the end we're having trouble with a brand new Bushmaster. It was a single shot. Tore the rims off every cartridge it was fed. They had some Tula junk and Winchester Q3131. Both of them same deal. They asked me to look over their rifle. Everything looked fine. I didn't have a .223 chamber brush with me, but I ran a .470 pistol brush into it and gave it a scrubbing to zero benefit. No help to you solving your problem, but I had to post the coincidence.

[500MAG]

DPMS recommends "excessive lubrication" on their BCG. Don't know if that's what is causing the problem.

[RKJ]

Jon I'm having the same problem with a PSA upper that I got awhile back. I was just about to give up (I still may) it shoots factory stuff just fine but my reloads were a no go. I finally read about pushing the shoulder back (so I did that,and it helped) but I also trimmed my brass back to 1.750and that has seemed to make all the difference. I believe you've got the right idea though,shoot the one that works!

[JonB_in_Glencoe]

500MAG,
What's a BCG ?

RKJ,
thanks for the hints, those will be the first things I try, If a vigorous cleaning isn't successful.

[quietmike]

Bcg=bolt carrier group.

If a good cleaning doesn't work, it sounds like a headspace issue.

Go/no go gauges would let you know for sure.

[country gent]

If you can find a few cases sized in a small based sizer it may help. I would blacken a case with a magic marker from extractor groove to case mouth and chamber it carefully and extract it carefully. The scrape and or rub marks should show the problem areas. A good chamber cleaning and chamber cast may show potential areas of problems also.

[popper]

Sounds like a chamber problem. If the Oracle won't take factory ammo, send it back. You'd want both chambers spec so you don't have to keep track of different ammo. I assume you have a case gauge for 223? You could change the Oracle barrel to 40WT or BO and have a lot of fun.

[merlin101]

I've had problems but not the same as your's. I've had two AR's that when new would fire one round and them jam. My solution was to remove the BCG and polish it with fine steel wool and oil, wipe clean and I was good to go! When I had this problem it took a while to notice the black finish on the BCG was a little rough and after polishing part of it you could easily see the difference.
Hope this helps someone.

[JonB_in_Glencoe]

Sounds like a chamber problem. If the Oracle won't take factory ammo, send it back. You'd want both chambers spec so you don't have to keep track of different ammo. I assume you have a case gauge for 223? You could change the Oracle barrel to 40WT or BO and have a lot of fun.

I don't have a case gauge.
I haven't gotten to giving this chamber a vigorous cleaning yet...that'll tell me something, as well as the tricks mentioned prior. I hope it's just a little grit in there?

When I read your statement about "both chambers spec" ...it got me to thinking, I remember the Sportical lower was stamped St.Cloud, MN and the Oracle lower was stamped Huntsville, AL.

Now I knew DPMS was sold and closed. Last fall, I bought these rifles from two different dealers, the one specifically told me he got a large quantity of them from an auction when DPMS St. Cloud closed. I never gave it a second thought about the other one.

So, a quick check at Wikipedia for DMPS...half way down the page was this...

DPMS's St. Cloud production facility with 115 employees was closed and production has been moved to Remington's new state of the art non-union facility in Huntsville, Alabama (https://en.wikipedia.org/wiki/Huntsville,_Alabama), which will employ 2,000 people in 10 years. Remington's Ilion, New York (https://en.wikipedia.org/wiki/Ilion,_New_York), production facility closed down two production lines for their Bushmaster (https://en.wikipedia.org/wiki/Bushmaster_Firearms_International) AR modern sporting rifle (MSR) and R-1 1911 pattern pistol and moved them to Huntsville.
Dang...the Oracle is a Remington.

If it does have a Chamber issue, I may talk with the Gunshop I bought it from, I'll see those boys at the Hutchinson, MN Gunshow in Sept. 2016...which will be the one year anniversary of me buying it from them (note to self: remember to bring the receipt). But I will not return it for repair to Remington. I'll consider alternatives before that, as I recall Boerranchers thread, oh so well.

http://castboolits.gunloads.com/showthread.php?290443-Going-back-a-4th-time

[imashooter2]

Dang...the Oracle is a Remington.



With my brand new Bushmaster story as a corollary. That new state of the art facility has sure turned out some lemons.

[Houndog]

Remington's parent company owns both DPMS and Bushmaster and are turning out some real garbage in my opinion. More than likely you will find an out of spec chamber in both cases. Do yourself a favor and find a gunsmith that does chambering work and let him check it out.

[starnbar]

For what it's worth I size all 5.56 to 1.750 and it solved the problem for me in a colt and a stoner upper I have.

[country gent]

Find an smith that specializes in accurizing the ar series rifles and have them check it out. If its not right have them do whats needed. (You may be able to set the barrel back and rechamber but then a special gas tube is needed). A accuracy smith with good refrences will give you the best rifle possible with the available components.

[leadman]

I have noticed that many molds cut these days are on the large size, especially on the ogive. Have you made a dummy round and blackened the boolit and try to run it into the chamber? I would also blacken the neck of the case. This may reveal the area that is preventing chambering. What is your sizer die reducing the boolits to? Have I normally size my 22 cal. boolits to .225", which work fine in my AR but my Contender 223 Rem will not take as long a case overall length without the boolit nose engraving in the rifling.

[JonB_in_Glencoe]

Leadman,
I size to .226
I will be trying the black marker trick once I get the chamber cleaned...more than likely on the case. But, the boolits I made for the first dummy round testing with were frosty, which show the marks pretty well. Both ARs scratch up the boolits pretty good, just cycling them into the chamber, but not the type of marks that the lands touching would create. I tried several different OAL for the dummy rounds, that's how I determine the OAL I want to go with. I did find the OAL maximum for the sportical, as mentioned in the OP.

[dkf]

The reamer was probably at the end of its life when the chamber was cut. If you run a good reamer through it to clean it up, the rounds should chamber fine. If your sizing die is not a small base you may be able to get the rounds to fit with a small base sizer if the chamber is tight closer to the case head.

[xacex]

Before calling it quits, and believing it is a chamber issue try swapping out the BCG between your two rifles. Sometimes these problems can be as simple as a bad extractor or missing parts in the bolt such as the extractor spring. If it does the same thing with the swapped bolt carrier group and ​factory ammunition then you can pretty much be certain it is a chamber that is out of spec.

[JonB_in_Glencoe]

Before calling it quits, and believing it is a chamber issue try swapping out the BCG between your two rifles. Sometimes these problems can be as simple as a bad extractor or missing parts in the bolt such as the extractor spring. If it does the same thing with the swapped bolt carrier group and ​factory ammunition then you can pretty much be certain it is a chamber that is out of spec.
ANother great idea, thanks...again, I should have thought of that.

[Jake70]

I've never had an AR that didn't just work out of the box.

[xacex]

I've never had an AR that didn't just work out of the box.
Rare, but it happens. With so many manufacturers pumping out parts tolerance stacking, and burs are the most common problem. Reamers wear, shaving get left in bolts or barrel extensions, burs are left in gas ports ect, ect. This is why I like building my own. I get to inspect all of the parts, and make sure the parts are good as well as clean and oiled. The only AR I had that did not run the first time I took it out was a 9mm build. It took a little more fitting with that one. I just did a 6.8 SBR build with a friend and we found a few slight issues that we had to work through. Shot just fine the first time, and every time but if it were a factory build they would have not caught the problems just slapping it together.

[molar]

Sounds like a chamber problem. If the Oracle won't take factory ammo, send it back. You'd want both chambers spec so you don't have to keep track of different ammo. I assume you have a case gauge for 223? You could change the Oracle barrel to 40WT or BO and have a lot of fun.

There are lots of reports of 5.56 and 308 DPMS guns having chambers so tight they have to be reamed.

[runfiverun]

must be buying their reamers from Lyman.

[JonB_in_Glencoe]

I finally got time to mess with the Oracle.

The short story is, looks like the Oracle's chamber is within spec, although seemingly on the tight side.

The complete story:
First I looked in the chamber with a good snake light.
I could see one large granule or Burr or something at about the halfway point of the chamber. It looked like the size of one granule of FFFF BP. Maybe a loose metal chip from machining?

I flushed the chamber with WD40, then blew it out with compressed air.
Then I put some CLP in there and then scrubbed it with a AR chamber brush and then ran a CLP soaked patch down the barrel with a brass jag. Then a few dry patches, then a big piece of flannel to dry the chamber. That speck was gone, chamber looked good, for what can be seen with naked eye and the snake light.

The results:
Mil Surp ammo cycled fine now.

The brass I used to make and re-make the dummy rounds(that I talked about in the OP), were now too long (.001 to .005 over 1.760). I'm not sure where they started out at? cuz when making the dummy rounds, after I FL sized them, I didn't check length, but should have. So today, I FL sized them again and then trimmed (and deburred)them to various lengths...and attempted to cycle the brass cases only (no bullet), from the magazine.

1.750 chambered fine.
1.755 chambered fine.
1.758 (what my Lee case length guage setup trims them too), chambered fine.
1.760 stuck in the chamber, just a tiny bit.
1.762 stuck ...and stuck good in the chamber.

I never took the time to set the shoulder back during FL sizing, since I had success with trimming to various sizes.

I didn't take the time to try any boolit ammo, since I will be using the other AR with a seemingly more roomy chamber, for that.

Thanks to everyone who offered helpful advice.
Jon

[sparky45]

JonB; a case gauge is your friend. I suspect most of your problem is that your cases are a bit over size for the chamber. I went through the same process with a tight chambered 300 blackout. Once I got the case gauge, the problem was quite noticeable. I also invested in a small base FL 223 die.

[JonB_in_Glencoe]

Sparky,
Case gauge: no doubt.

But I got 'er solved now ....and as long as it works fine with mil surp ammo, I'm fine. I'll just use the other rifle for CB loads.

Next up is range testing of both, to confirm.

[W.R.Buchanan]

John: you said you didn't set the shoulder back when You F/L Resized? You kind of need to. Run the die down until it touches the shell holder just before the press cams over center at the bottom of the stroke.

Next if your cases are longer than 1.76 after F/L sizing they will run into the front edge of the chamber. With a bullet in place it will pinch the bullet and cause a pressure spike. NO NO.

OAL on these is more about feeding from the magazine. Cartridges longer than 2.250 will probably run into the front of the mag and cause problems. Anything shorter should feed just fine.

You could get by not bumping the shoulder back if you were shooting a Bolt Gun with some mechanical advantage as it goes into battery. Not the case with a Semi Auto as it only relies on the spring to close the bolt.

It sounds like your root problem is not F/L sizing completely.

I see trying to get Cast boolits to work in these guns to be an exercise in futility. The feed ramps are nothing more than little grooves cut at 4 and 8 O'clock in the back of the barrel and they wouldn't be very lead friendly in any event.

Randy

[JonB_in_Glencoe]

Randy,
what I meant was setting the shoulder back farther than Spec.
Besides my standard FL die, I have one that was modified by the previous user(removed about 1/4" of the bottom of the die, so it can be adjusted lower).

Thanks for the hints...much apreciated.
Jon

[popper]

If you don't like slam fires, get a case gauge and check them all. A cast 308 will make a 1/2" deep crater in concrete.
Edit:Set you die to FL size the smaller/factory chamber. GKs both have Weatherby 243 and have different chambers. Got to size to smaller or they will switch ammo and get jam.
Oh, get a chamber brush if you don't have one.