Troubleshooting two new builds

[John800]

I build two 6.5 grendel ar 15s a few months ago and am having issues with both of them. Both are anderson lowers with ar stoner and schmid tool parts kits. I have also tried them on a known working 5.56 dpms lower. And no change.
First is an ar stoner 16” upper and it does not cycle, the bolt is locked and can not be cycled by the charging handle after firing.
The second is a bear creek arsonel 18” side charging upper and it stovepipes and double feeds or it rams the empty case into the ejection port. After doing some research online and thinking it may be over gassed I installed a jp adjustable gas block. After installing the block it acts like the first one, it doesn’t cycle no matter the gas block setting. This one you can usually cycle it by hand and eject the case.
Any suggestions? Bca and midway have both failed to respondand
Does anyone know the correct size for gas ports with these combos.

[VASCAR2]

Last I knew Midway AR Stoner is rebranded Bear Creek Arsenal. I’m curious if these barrels are stainless steel or Chrome Moly Vanadium steel barrels? The 18” mid length gas port size I have is .078”, rifle length is .094” minimum. The 16” carbine length gas port .0625” and 16” mid length gas port .076”-.078”.

I would remove the bolt carrier from both barrels. Get a fresh factory cartridge and drop the cartridge into the chamber and ensure it is fully seated. Raise the muzzle and see if the cartridge falls out of the chamber under gravity. If the cartridge fails to fall out use a cleaning rod to push out the cartridge. If it takes minimal push to have the cartridge fall out you might clean the chamber. The chamber could be rough and it might help to polish the chamber. I use Flitz polishing compound on a barrel mob attached to a short cleaning rod spun by a hand drill. Re-clean the chamber and barrel and retry putting the cartridge in the chamber to see if the cartridge now falls out under gravity.

If the cartridges still sticks use a black marker to color the bullet and cartridge neck and see if the rubbed off black marker indicates the bullet is jammed into the lands. If the bullet is jammed into the lands the chamber is probably out of spec. If the manufacturer uses the same tool to long the cutting surfaces don’t cut deep enough resulting in a short chamber. This is a relative common problem with mass produced barrels where quality control is lacking.

It is possible the bolts/BCG are out of spec if the cartridges fall out of the chamber under gravity. It is also possible the gas block and alignment pin are not square and inline so you have insufficient gas. It is possible the gas block is not centered over the gas port resulting in insufficient gas. I’d inspect the carrier key and bolt carrier for carbon from gas seepage caused by the carrier key not being installed properly.

[montana]

Last I knew Midway AR Stoner is rebranded Bear Creek Arsenal. I’m curious if these barrels are stainless steel or Chrome Moly Vanadium steel barrels? The 18” mid length gas port size I have is .078”, rifle length is .094” minimum. The 16” carbine length gas port .0625” and 16” mid length gas port .076”-.078”.

I would remove the bolt carrier from both barrels. Get a fresh factory cartridge and drop the cartridge into the chamber and ensure it is fully seated. Raise the muzzle and see if the cartridge falls out of the chamber under gravity. If the cartridge fails to fall out use a cleaning rod to push out the cartridge. If it takes minimal push to have the cartridge fall out you might clean the chamber. The chamber could be rough and it might help to polish the chamber. I use Flitz polishing compound on a barrel mob attached to a short cleaning rod spun by a hand drill. Re-clean the chamber and barrel and retry putting the cartridge in the chamber to see if the cartridge now falls out under gravity.

If the cartridges still sticks use a black marker to color the bullet and cartridge neck and see if the rubbed off black marker indicates the bullet is jammed into the lands. If the bullet is jammed into the lands the chamber is probably out of spec. If the manufacturer uses the same tool to long the cutting surfaces don’t cut deep enough resulting in a short chamber. This is a relative common problem with mass produced barrels where quality control is lacking.

It is possible the bolts/BCG are out of spec if the cartridges fall out of the chamber under gravity. It is also possible the gas block and alignment pin are not square and inline so you have insufficient gas. It is possible the gas block is not centered over the gas port resulting in insufficient gas. I’d inspect the carrier key and bolt carrier for carbon from gas seepage caused by the carrier key not being installed properly.

Excellent explanation, poorly reamed chambers/headspace are quite common..There can be other variables but this is a good start..

[John800]

I will check into those things, thanls for thehelp. Also one thing to note: they are both having failures every single time, not just occasionally.

[Bonas]

You're going to have to isolate variables one at a time. Start with good quality factory ammo. As noted above, check the chambers. If the cartridges drop freely, move on to ensuring the gas block and gas port are correctly aligned. Troubleshoot with the known-to-work lower. Make sure it has a standard buffer and a standard, good quality buffer spring. Borrow a bolt and a magazine that are known to work. Report back. For the barrel that won't eject at all, you can hand feed the round until it ejects.

Check the lowers' function on uppers known to work. If everything, checks out, and they still won't cycle, consider buying some good headspace gauges, if you can find them.

While it won't help you now, this kind of stuff is why I only use good quality parts anymore. Low end parts are a false economy, in my opinion. I've been where you are, and I avoid it now.

[LRRPF52]

This is an example of why I tell people to not waste their time with low-end, low price point critical components from vendors who clearly don’t give a rip about the quality of their products and are operating on high volume sales models.

It’s just not worth the time, ammo, range fees, and gas.

I have tried to get some garbage barrels to work for people in the past, and they were nothing but trouble, back-and-forth to the range, tried to fix with adjustable gas, and it just never worked out.

It takes me a little over $100 to fill the tank. Range fees are between $10-$20. Targets are $1 per. Ammo is anywhere from $23 to $33/box.

A crap barrel is a net negative, meaning you will walk away with less money in your pocket for a negative set of performance.

I don’t ever want the performance outcome to be a negative, starting with reliability, followed by accuracy and precision. That’s false economy, as Bonas said.

If I’m paying all of those recurring fees, it only makes sense to end up with a reliable and accurate AR-15.

The crazy things is, you can get lower price point options that are proven if you want to got that route.

I have had surprisingly-good experiences with several of the Faxon group buy barrels we did here on the forum, as well as the higher price point Lilja barrels of course.

My personal advice for turds is to flush them and move on. It’s simply not worth the continued negative experiences you will have.

[Steve_evetS]

I will check into those things, thanls for thehelp. Also one thing to note: they are both having failures every single time, not just occasionally.

Hi did you find out what the problem was?