A little problem with my new AR upper...help? * View * Edit

[mythaeus]

I finally completed my upper yesterday. However, when I go chamber a round (with the new BCG) and try to eject it, I cannot pull the charging handle back. I had to separate the upper and lower completed and pull it back really hard to get the round ejected. When there isn't a round chambered, the movement is fine/normal. I used another BCG and it worked just fine and ejected properly with normal ease. Is there something wrong with the ejector? I didn't shoot the gun because I didn't feel right about it. Thoughts? Thank you.

Al

[gold cup abuser]

few random things come to mind here....


the bcg is functioning without a round in the chamber.

with a live round in the chamber the bcg will not cycle and eject the round unless you manually take out the bcg.

If this a correct summation I would check the following:

1. inspect the chamber of the rifle for any type of burrs, marks or other blockages such as packing grease or powder residue.

2. check the bcg to confirm you have done the following correctly:

a. the gas rings on the bolt are on and the open clips are NOT lining up with each other.
b. check the gas tube to confirm its staked properly in place.

3. look on the barrel for caliber markings and twist rate ie 5.56 NATO 1/9 or something to that effect.

4. if these check out then have the rifle head spaced BEFORE you attempt to fire it.

I don't know who mated the barrel to the upper receiver and if the bcg group you have is what came with the kit, so if both of the above pass visual then its head space time....

as a side note bcg's are not to be interchanged between rifles. while there is some slop in AR 15 head spacing, I would not want to be a victim of 'tolerance stacking' where all of the parts together exceed manufactures spec for dimension and size lol

[mythaeus]

Thanks GCA!

I bought the barrel and the complete BCG from Tony's Custom at the VF Gun Show and he assured me that the headspace is checked. I'll definitely do that now on my own before firing it as you said.

I've disassembled the BCG and doubled checked everything and it looks OK to me (as compared to my other BCG). I also checked for burr and potential blockages as you said and didn't see anything. If there were blockages, I'd think the other/older BCG would have the same issue. Thanks again for your advice.

Al

[Legion_Prime]

Take the BCG out look at it so the bolt face is towards you with the gas key on top. Which side is the extractor on? Some bolts are not made to spec and can be installed upside down. If the Extractor (claw) is on the right and the ejector (pin) is on the left you may have your culprit.

[mythaeus]

Take the BCG out look at it so the bolt face is towards you with the gas key on top. Which side is the extractor on? Some bolts are not made to spec and can be installed upside down. If the Extractor (claw) is on the right and the ejector (pin) is on the left you may have your culprit.

Excellent point and I have already checked that. I've compared everything one for one with the other BCG that I have and everything looks EXACTLY the same. I'm looking to buy a headspace gauge set to check the headspace for the time being. What do you do in the case that the headspace is off?

Al

[Suburban]

What do you do in the case that the headspace is off?

Al

Try another bolt. If you try 3 different bolts, and still can't get the headspace right, consider returning the barrel. If the chamber's too short, and it's not a chrome-lined chamber, you can ream it to correct the headspace.

[mythaeus]

Well...just got back from the range. After successfully chambering and ejecting 5 rounds of Wolf .223, a Remington UMC .223 round got stuck so hard that I couldn't get it out even with the upper separated. I asked a guy who works at the range to take a look and he decided to fire it (he's been building his own AR). I told him that's it's my first build, everything is new, never been fired, the problem, etc, etc... He fired it anyway. That was all it took! I put another 50 rounds through without a hiccup or problem. It seems to me, given the casing gets all scruffed up, that the chamber is just too "new". I've been so wiredly worried, but I can breathe now and am ecstatic! Thank you all.

Al

[Legion_Prime]

probably a burr in the chamber then, give it a good cleaning with a GI chamber brush by hand. if it's still scuffing it up and cases are not ejecting then I'd go find someone with a reamer to give it a whirl. I just always say check the simple stupid stuff first.

[mythaeus]

probably a burr in the chamber then, give it a good cleaning with a GI chamber brush by hand. if it's still scuffing it up and cases are not ejecting then I'd go find someone with a reamer to give it a whirl. I just always say check the simple stupid stuff first.

There must have been quite a few, small enough to not be noticeable because the scruffs were pretty harsh. The steel-cased Wolf got out a little easier because of the polymer coating; whereas, the soft brass cases were "gripped". Well, the gun cycled flawlessly at the range and I can now unchamber a chambered round with relative ease. Problem is solved, but I'm putting at least another 50 rounds through this baby before calling it solved.

Al

[Warners Surplus]

SAND in the chamber!! Clean, Clean,Clean!!


I won't mention the supplier but I just had a few M4 barrels come in and after assembly I headed out to test fire as always. I had 2 barrels do the same thing that yours is doing. I pulled them back apart and there was real fine sand in the chamber and barrel. It seems they are cranking barrels out so fast right now that some idiot forgot to clean the blasting sand out of them before AND after the finish was done.

I am dam glad that yours wasn't as bad as one I had because there was so much sand in that barrel that just saying screw it and firing it surely would have been damageing if not deadly.

Rich W.