Maybe I just wasn't meant to build Ar's

[Slatewiper]

I just finished my build and grabbed a cartridge to be sure it would chamber. Loaded it into a mag inserted it into the rifle with the bolt back and released the bolt. The bolt wouldn't go all the way forward and when I pulled the charging handle back it wouldn't budge. I ended up removing the buffer assembly and the bolt was at least 1/4 to the rear of where it's supposed to be. I removed the pivot pin so the rifle would come apart and ended up having to tap the carrier with a punch to get it to slide back. When it did the cartridge slid out of the barrel.

What might of happened to cause this?

[rcase1234]

Couldn't exactly tell you the issue just on pure explanation. Could you upload some pictures? However, do not feel discouraged! Trust me I've had issues also in the build process just got be patient and do a little "fine tuning" is all :)

[Sasahara]

Does it cycle fine without the cartridge? How about with just the carrier? Can you give us a complete (and thorough) parts list?

[Slatewiper]

Does it cycle fine without the cartridge? How about with just the carrier? Can you give us a complete (and thorough) parts list?

It's a BCM upper on top of an Anderson lower. Barrel is a faxon 18" rifle gas with a YHM gasblock. BCG is a Griffin armaments. It cycles fine without a cartridge. Charging handle is a BCM Gunfighter.

[rocket 442]

Pull the gas tube roll pin & make sure the gas tube hole lines up with the hole in fsb or gas block. I recently had a similar thing happen.Gas tube moved back while I installed the pin.

[Slatewiper]

Pull the gas tube roll pin & make sure the gas tube hole lines up with the hole in fsb or gas block. I recently had a similar thing happen.Gas tube moved back while I installed the pin.

Gas tube is fine in that regard. I have not fired the rifle yet. It won't chamber a round.

[KUSA]

Do it again, take the pins out, and take a picture of it stuck.

[JS-Maine]

The upper won't separate from the lower if the BCG isn't forward of the buffer tube, but it would be helpful to see a pic of the malf. Does the ejector move freely in/out of the bolt face? What do the feed ramps look like? Can you hand-feed a round into the chamber?

[MistWolf]

Make sure-
-it's the right ammo and the right chamber.
-there are no obstructions in the chamber.
-your bolt is not installed 180 degrees out in the carrier
-there is no interference from the charging handle

[Rifleman_04]

Are you using a live round or dummy? Look at the chamber.

Btw look up mortaring so you don't have to tear your gun apart when you get a round stuck.

[Slatewiper]

The upper won't separate from the lower if the BCG isn't forward of the buffer tube, but it would be helpful to see a pic of the malf. Does the ejector move freely in/out of the bolt face? What do the feed ramps look like? Can you hand-feed a round into the chamber?

Not sure what the malf is. Ejector does move freely and I can hand feed a round into the chamber but can't tell if its fully seated.

[Slatewiper]

Are you using a live round or dummy? Look at the chamber.

Btw look up mortaring so you don't have to tear your gun apart when you get a round stuck.


Live round.

[Slatewiper]

Make sure-
-it's the right ammo and the right chamber.
-there are no obstructions in the chamber.
-your bolt is not installed 180 degrees out in the carrier
-there is no interference from the charging handle

It's a 5.56 chamber and I was using a .223 cartridge. Bolt is seated in the carrier properly. It was an American Eagle round so kind of on the cheap side.

[sevenhelmet]

Do you have another bolt+carrier you can swap in? Switching the BCG with another gun might help you with your diagnosis.

[MountainRaven]

I would strongly, STRONGLY recommend you pick up some snap caps before going any further with function testing. Even the el cheap Magpul plastic ones that come with half their stocks work fine.

[Onyx Z]

Since it cycles fine without ammo, it sounds like either the ammo or chamber/bolt is out of spec. You either have a very short chamber headspace or the brass shoulder on the ammo is sized/headspaced too long. What typically happens in this type of malfunction is the shoulder of the brass casing is jammed into the shoulder of the chamber when the BCG drops and the round gets wedged in there. If the bolt face is longer than necessary or the chamber is shorted than necessary, the chamber is essentially shortened. I'm 99% sure your chamber is out of spec.

I would try a different ammo first and re-check. Then a different bolt. If neither of these work, the chamber/barrel is most likely out of spec. Do you have a Case Length Headspace Gage? (http://www.midwayusa.com/product/456614/le-wilson-case-length-headspace-gage-223-remington?cm_vc=ProductFinding)

[mtdawg169]

Is the carrier binding on the gas tube? Remove the upper, disassemble the bolt carrier group and reinsert the carrier only. Does it slide freely without resistance and go all the way into battery?

[sevenhelmet]

I would strongly, STRONGLY recommend you pick up some snap caps before going any further with function testing. Even the el cheap Magpul plastic ones that come with half their stocks work fine.


A MAJOR +1 to this. I never, ever chamber live rounds for a function check on a new firearm until I have established that it functions with a dummy round first. Doing your first actual function check with live ammo is a great way to have an inadvertent discharge. Wish I'd put this in my post earlier.

[LRRPF52]

My suspicion is the same as Onyx z, a short chamber cranked out that slipped through the cracks.

If the gun isn't going into battery with a known brass-cased cartridge, there are some dimensional problems in this scenario more likely than not.

Do not attempt to shoot it. This needs time and competence to diagnose and correct.

[Slatewiper]

Thanks for all the replies. I switched out ammo to a 77gr Sierra OTM and it chambered fine. Also used a couple of others that worked as well. I just grabbed the nearest box at first which happened to be cheap stuff. I think that was the culprit. Bill at Faxon sent me a PM offering to check things out which I think speaks highly them.

[sevenhelmet]

I would have them check it. Cheap ammo should still chamber properly. I think something is out of tolerance.

[FaxonNathan]

It's a BCM upper on top of an Anderson lower. Barrel is a faxon 18" rifle gas with a YHM gasblock. BCG is a Griffin armaments. It cycles fine without a cartridge. Charging handle is a BCM Gunfighter.

We're sorry to hear of the issue! We took the liberty of pulling our Q/C records for the 18" barrels. All were 100% checked on headspacing and passed MPI.

As such, it could likely be one of the following:
1. Headspacing issue, likely related to the bolt face depth. Do you have a set of guages or a set of calipers that were used to check the rifle prior to assembly?
2. Ammo related. What ammunition do you have and has it worked in other rifles?

[oneeek020]

And this is why I love This form, not only has quality information been given to you but the manufacture responded as well!


Sent from my iPad using Tapatalk

[Singlestack Wonder]

I would have them check it. Cheap ammo should still chamber properly. I think something is out of tolerance.

+1. These issues are usually not seen with tier 1 barrels such as BCM, Daniel Defense, Colt, Noveske, etc.

[FaxonNathan]

+1. These issues are usually not seen with tier 1 barrels such as BCM, Daniel Defense, Colt, Noveske, etc.

We appreciate the perspective, and will hold ourselves everyday to their example and better. We take our ISO and AS quality controls seriously. Some of the companies you mentioned actually don't make their own barrels. They use companies like us (and us in some cases, actually us).

We are most curious the depth of the bolt face and further, if there is an issue with the ejector pin/spring. We have seen instances in cases where bolt is good to go but the cross pin used on the ejector is installed incorrectly or the pin does not match the bolt and cannot recess fully or at all.

If the issue ends up being his barrel, we will gladly replace it and further, tell people what happened and how we plan on avoiding it.

[MistWolf]

The easiest answer is often the correct answer. I'm willing to bet it's a case of the "Noobie with New Rifle Blues", nothing more. Sometimes you just fat finger the new toy. But until that is eliminated as the problem, there's no sense in anyone getting worked up about it.

Slatewiper, clean the chamber and shoot a couple of mags with ammo that works through your upper and see if there are any hiccups. I'm willing to bet it's not the barrel

[Slatewiper]

The easiest answer is often the correct answer. I'm willing to bet it's a case of the "Noobie with New Rifle Blues", nothing more. Sometimes you just fat finger the new toy. But until that is eliminated as the problem, there's no sense in anyone getting worked up about it.

Slatewiper, clean the chamber and shoot a couple of mags with ammo that works through your upper and see if there are any hiccups. I'm willing to bet it's not the barrel

Took it to the range today and fired about 50 rounds (about half 55gr FMJ and half 77gr OTM) and had zero issues. The cartridges that first caused the problem cycled thru my LWRC with no problems.

[TF82]

When you were hand cycling, were you using the charging handle to attempt to chamber the rounds or were you locking the bolt back, inserting the magazine and releasing with the bolt release?