First built AR-15 won’t chamber next round

[Stryker]

And before you mess with springs/buffer weights, make sure the gas block is properly aligned on the barrel.

One of the first AR's I built had this issue - I had not properly aligned the gas block to the port and because I was obstructing part of the port, was only getting partial blowback to the bolt and had the exact same issues that the OP is seeing. FIxed the alignment and no issues going forward.

 

[pastera]

Could be too little gas... which can be fixed by playing with the spring and buffer if the gas block isn't adjustable. If you have access to a borescope, you might make sure the gas port isn't blocked or misaligned.

This
Had similar issues on a 16" 300BLk upper (pistol length gas)
Fix was to disassemble the BGC and scrub the shit out of and remove the gas block to align clean the gas system.

OP:
Try doing a detailed clean/lube of the BCG and blow out the gas system with compressed air. A PITA but can be done by attaching a hose to the gas tube in the upper receiver.

 

[dw617]

Copied and pasted from White Oak’s FAQ. This may help OP shed some light on the issue.

Also, if this is a new upper, lube the hell out of it.

How to identify a short cycling issue​

One of the questions we get a lot is “Why doesn’t my bolt lock open when I fire the last round in the magazine?” Here is a simple test to help you identify the cause.

• -A live round must be fired for this test so you must be in an appropriate location to perform this test.
• -Manually lock the carrier to the rear by pulling the charging handle to the rear and depressing the small tab on the bolt catch.
• -Insert one round into a magazine and then insert the magazine into the rifle.
• -Close the bolt by depressing the large tab on the bolt catch or by pulling the charging handle to the rear and releasing it.
• -While applying pressure to the small lower tab on the bolt catch, fire the round in a safe direction.

If the carrier locks to the rear with the bolt stop engaging the front of the bolt, then there is an issue with either the magazine or the bolt catch being used or the lower receiver. It is not a short cycle issue.
If the bolt does not lock to the rear or engages on the front of the carrier, then you do have a short cycling issue.

 

[pastera]

AR-15 won’t chamber next round

I recently built my first AR-15. It’s a BKF complete 14.5 upper with a Muzzle device pinned and welded on an Anderson lower I assembled myself from a lower parts kit. Has a standard carbine buffer and buffer spring. After firing it’ll eject the spent round but won’t load the next round in the magazine. It does indeed charge the gun because I can pull the trigger afterwards and it still clicks. In order to load the next round I have to eject the mag and reinsert it in order to manually charge the gun and allow the BCG to pick up the next cartridge. I was thinking I may need to switch out either the buffer or buffer spring from standard to some sort of combination of either heavier or lighter buffers or springs. Am I correct in this assessment? If not, what could be the issue? If so, what combo would I need to use? H1, H2, H3, Sprinco Blue, Yellow, Green, etc? Any help is greatly appreciated.

Swap the upper onto another lower and test to see if the problem follows the upper
If you don't have another AR, shame on you. Post up location and see if someone will kindly help you out by meeting at the range with a known good system to swap lowers.

 

[CrackPot]

1) under gassed. check gas hole diameter and gas block alignment. Check gas tube to gas key alignment.
2) too much resistance. clean and thoroughly lube. Check for interference between mag lips and bcg. Check weight of buffer and buffer spring. Check for resistance inside the buffer tube with the buffer
3) other (rarer). is the shell casing being deformed on use? Headspace, could have leakage or issues there

I would take the suggested approach of a working AR and swaping mag (with ammo), upper, lower to try and isolate to one of the three and then go back to the list to see what could cause the failure within that part.

My range debug setup is most spare parts in a box plus another functioning AR. It is always possible to isolate the source of the issue. Misaligned gas block happens a lot more than you think...

 

[pastera]

i prefer not to talk to your kinds, and you are actually on my ignore as well. so you do you.

overall, then, it just makes sense with any gun to know how to do its full disassembly and re-assembly and to do that on the brand new gun, if not for safety - then for your own education.

on a dirt cheap ar15 uppers specifically, disassembly is usually helpful, as you make sure all bolts were actually torqued in and not hammered in, literally.
you'll also put a proper lube under a barrel nut to torque it to prescribed amount, i would also be getting the upper receiver lapped , as it also just a good thing to do. then torque it all back together - properly, with gas block sitting on properly.

when you have all the tools, whole thing would take 30-40 min top, it is a very simple procedure. and everything usually cycles properly after that, ejects like it should, and causes no questions on forums of why standard stuff exhibits non-standard behavior. an ar15 is an extremely simple design, not to know how to deal with it has little to no excuses.

When you lube a threaded joint the torque required lowers
Do you have the proper torque for the barrel nut lubed with the type of lube you use?
Or did you wing it?

But you are right - if it doesn't run right then pull it apart to inspect, clean and reassemble per specifications so you know it's done right.

 

[Joeldiaz]

What the...This is an indoor range I'm guessing?
If it's an outdoor range then just quickly look to your side after shooting to see where the brass lands.

And shooting an AR indoors is awful. I hate shooting indoors regardless of caliber, much prefer being outside in the nice weather.

Yes it’s an indoor range.

 

[Marty McFly]

Yes it’s an indoor range.

Well as everyone has already said. @Tinkermatic biggest complaint about me. Short-stroking.

 

[paul73]

When you lube a threaded joint the torque required lowers
Do you have the proper torque for the barrel nut lubed with the type of lube you use?
Or did you wing it?

But you are right - if it doesn't run right then pull it apart to inspect, clean and reassemble per specifications so you know it's done right.

a torque # given for the barrel nut always presumes a proper assembly procedure, and that procedure uses lubricated joint.
i set wrench to 70-75, and it seems to work fine. first push it tight but no click, undo, then push all the way until the click, done.

 

[Supermoto]

whoever buys cheap 'deal' complete uppers and does not take them completely apart is doing it on his own risk.
i wrote up step by step what to do, but deleted it later, as those who want to fix it - will find instructions of how to fix it.
it is all rather simple and doable.

Lol My cheap upper works, better take it apart....clown shoes

 

[Hustler One]

A lower is a lower is a lower. Ive never seen a lower cause cycling issues unless their was a catastrophic failure of the trigger group or it was completely out of spec. I cant even believe some of you suggested that lmfao! Could be a mag issue but unlikely and if it is it should be fixed by now. The problem is it's a pos budget company. Next time go with BCM or get a complete upper from LMT, Colt, Knights etc..

 

[PioneerHD]

Try different ammo and...
Use a known-to-be-good magazine

Use a known to be good upper.

 

[pastera]

a torque # given for the barrel nut always presumes a proper assembly procedure, and that procedure uses lubricated joint.
i set wrench to 70-75, and it seems to work fine. first push it tight but no click, undo, then push all the way until the click, done.

I agree - tech manual calls our a specific grease with anti gall compounds
Some places call out antiseize which is most likely fine for a semi auto
But a lot of places simply say grease which is not okay if you expect to disassemble in the future

 

[paul73]

I agree - tech manual calls our a specific grease with anti gall compounds
Some places call out antiseize which is most likely fine for a semi auto
But a lot of places simply say grease which is not okay if you expect to disassemble in the future

yeah, that stuff is quite expensive. i use it also on the vertical screw rods on my 3d printers. good stuff. it`s a small packaging, but it lasts forever.

AeroShell 33MS / 64 Gun Grease .5oz / Mil-Spec for Barrel Nut Thread​

Amazon product ASIN B01GGQMF54View: https://www.amazon.com/gp/product/B01GGQMF54

 

[Marty McFly]

Can we all just get together and tear this thing down already?

 

[PappyM3]

A lower is a lower is a lower. Ive never seen a lower cause cycling issues unless their was a catastrophic failure of the trigger group or it was completely out of spec. I cant even believe some of you suggested that lmfao! Could be a mag issue but unlikely and if it is it should be fixed by now. The problem is it's a pos budget company. Next time go with BCM or get a complete upper from LMT, Colt, Knights etc..

There have been out of spec Anderson lowers. It’s not an impossibility. As I mentioned, I don’t think that was the issue, but you can’t say a lower is a lower is a lower.

 

[Joeldiaz]

Can we all just get together and tear this thing down already?

I’d love to set up a meet and greet where everyone takes turns tearing apart my rifle and telling me how bad of a job I did building my first AR

 

[Marty McFly]

I’d love to set up a meet and greet where everyone takes turns tearing apart my rifle and telling me how bad of a job I did building my first AR

Can't be as bad as my first. Well mine functioned fine. So nevermind

 

[paul73]

Can we all just get together and tear this thing down already?

most of us here are an anti-social bunch.

 

[Marty McFly]

most of us here are an anti-social bunch.

I volunteer as tribute

 

[PappyM3]

a torque # given for the barrel nut always presumes a proper assembly procedure, and that procedure uses lubricated joint.
i set wrench to 70-75, and it seems to work fine. first push it tight but no click, undo, then push all the way until the click, done.

Generally recommended to cycle it a couple more times before final torque. Also, 75 Ft/lbs is quite high. Yeah, still in spec, but dang.

 

[pastera]

Search for Aeroshell 64 (the 'new' designation for 33MS)
$28 for a 14oz tube

 

[PioneerHD]

Is OP using normal ammo, I've had this problem using shit ammo before prevented rifle from cycling .

 

[paul73]

Generally recommended to cycle it a couple more times before final torque. Also, 75 Ft/lbs is quite high. Yeah, still in spec, but dang.

i found that 75 works best - fixed my 20" larue issues, that had some sporadic fliers and groups spreading.
a proper lapping is still a key, though. pressing it in couple more times - not sure if it helps anything, you will only shift it around ad dent aluminum edges more, a pre-press and then good solid proper press works, a it just holds whole damn thing together in one spot.

did same to my .308 and 6.5CM AR10s, all shoot very well in 1/2-1/3moa, with consumer grade barrels.

 

[Joeldiaz]

Is OP using normal ammo, I've had this problem using shit ammo before prevented rifle from cycling .

Winchester .223 62 grain

 

[Supermoto]

A lower is a lower is a lower. Ive never seen a lower cause cycling issues unless their was a catastrophic failure of the trigger group or it was completely out of spec. I cant even believe some of you suggested that lmfao! Could be a mag issue but unlikely and if it is it should be fixed by now. The problem is it's a pos budget company. Next time go with BCM or get a complete upper from LMT, Colt, Knights etc..

Yeah, the guy that spent just over $200 on an upper is going to buy a $2000 KAC upper.

 

[Hustler One]

Yeah, the guy that spent just over $200 on an upper is going to buy a $2000 KAC upper.

I gave three (3) other options. The f***?

 

[PioneerHD]

Winchester .223 62 grain

Give us an update. Do you have another ar15 upper and lower to prove which piece is the trouble?
And can you use another mag and give us update

 

[chris_1001]

I’d love to set up a meet and greet where everyone takes turns tearing apart my rifle and telling me how bad of a job I did building my first AR

In!

 

[Joeldiaz]

Give us an update. Do you have another ar15 upper and lower to prove which piece is the trouble?
And can you use another mag and give us update

No other upper or lower to try out. Don’t think it’s a mag issue, but I only tried out old prebans so I can’t rule that out entirely.

I reached out to BKF customer support about the gassing concerns and they said they’d get back to me after communicating with their assembly manager to get their opinion on the issue. In the meantime I’ve gone ahead and ordered a bunch of different weighted buffers and springs and will play around with them to see if I can mitigate the issue while I wait. I plan on doing some future builds for myself anyway after I get this squared away.

I’m hesitant to mess with anything regarding gas myself so I’d rather wait for BKF to respond and send it back to them if it ultimately needs to be done.