First built AR-15 won’t chamber next round

[xtry51]

99% it's gas related. Make sure the gas block is aligned. Maybe pull it forward and ensure there isn't a burr in the barrel port and reseat it. Then go to a lighter buffer.

If you have a newer cell phone, have someone take a super slow mo video of a round being fired close to the ejection port. You'll be able to see if the bolt is fully cycling.

 

[Joeldiaz]

Just for confirmation, there was no “H” or “H2” printed on the face of your buffer, right?

Correct, it’s just a standard buffer.

 

[sschevy]

Horse shit. You're talking shit about a company that you yourself admitted that you know absolutely nothing about--and as a business owner yourself, you should be more careful than that.

A quick scoll through their web page shows that BKings sells uppers both with and without bolt carrier groups.

I directly asked OP about the provenance of his bolt carier group in my first post, and he did not answer the question. And it absolutely matters, right? I'm guessing it certainly would matter if it was YOUR shops upper build and YOUR shops reputation getting shit on, right?

If OP tossed a shit-tier bolt carrier group with shit-tier quality control into his BKings 14.5" midlength gas system upper then that's on him--and not BKings, right?

I'd say if the rifle runs with a known-good bolt carrier and the gas impulse provided by 5.56 NATO ammo then they've done their duty to their customer. And if it doesn't, well, they haven't--and they need to make it right, whatever that takes.

If it were my shop I would NOT tell him to band aid the problem with a lighter non standard spring and buffer

I’d take it back , troubleshoot it and fix it promptly …all while he waited and watched me do it

I’ve done it dozens of times for people over the years , even on firearms they didn’t buy from me , at no charge


So ya , I’m shitting on someone who obviously isn’t standing behind their product

 

[50wt]

I’ve done it dozens of times for people over the years , even on firearms they didn’t buy from me at no charge

Right there in plain sight for the op to see.

 

[Uzi2]

Correct, it’s just a standard buffer.

A standard rifle buffer or standard carbine buffer?

 

[50wt]

A standard rifle buffer or standard carbine buffer?

Rifle would be too long to cycle by hand wouldnt it

 

[Uzi2]

Rifle would be too long to cycle by hand wouldnt it

I don't think he mentioned which buffer tube/stock was on the gun and yes, a rifle buffer in a carbine tube will only travel rearward about 2 inches, not even enough to clear the ejection port.

Trying to squeeze out some more info from the OP instead of being fed one tid bit at a time with each post.

 

[Joeldiaz]

A standard rifle buffer or standard carbine buffer?

Standard carbine

 

[Joeldiaz]

I don't think he mentioned which buffer tube/stock was on the gun and yes, a rifle buffer in a carbine tube will only travel rearward about 2 inches, not even enough to clear the ejection port.

Trying to squeeze out some more info from the OP instead of being fed one tid bit at a time with each post.

It’s a BCM Standard Carbine Buffer kit. Comes with a carbine buffer, buffer tube and buffer spring.

 

[Dennis in MA]

Nice thread. I gotta dig out my Bushy Carbon15 that did the same thing. It's been in the back of the safe for near forever because I just haven't got a round tuit to futz with it.

 

[50wt]

The world will never know

 

[Supermoto]

Nice thread. I gotta dig out my Bushy Carbon15 that did the same thing. It's been in the back of the safe for near forever because I just haven't got a round tuit to futz with it.

I got one sitting in the back of the safe also. It has too many proprietary parts to be worth the effort

 

[silversquirrel]

Cmmg .22 lr Tesla conversion. No gas required. Done.

 

[Hustler One]

@Warm_Garand stand down. OP said it was a COMPLETE upper.

 

[mcshooter]

I've had it happen on a build when I was new.

Mil spec receiver.

Commercial stock.

Do you have a photo

 

[mcshooter]

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.

Do you want to try and diagnose this? I'll be able if you come to my range and by me coffee

 

[pastera]

99% it's gas related. Make sure the gas block is aligned. Maybe pull it forward and ensure there isn't a burr in the barrel port and reseat it. Then go to a lighter buffer.

If you have a newer cell phone, have someone take a super slow mo video of a round being fired close to the ejection port. You'll be able to see if the bolt is fully cycling.

Easier is put a single round in the mag and see where the bolt ends up

 

[Tinkermatic]

Unfortunately I’m not really sure, I don’t have a 2nd person available to watch me shoot and the range I went to doesn’t allow recording

Don’t need a second person for this. Is the brass trickling out right next to you? Going straight up? Behind you? Or taking a page out of the PTR 91’s book and launching it into next Tuesday?

The reason I ask, is that while many people think it’s under-gassed and short stroking, the symptoms of an over-gassed gun are similar. The brass can be the key. Over-gassed and you may have premature bolt unlocking which can jar the brass loose of the ejector and it just plops right next to the gun. It’ll also fail to strip the next round due to bolt speed, or it’ll cause a feeding malfunction and the round won’t chamber properly. Under-gassed can do the same thing but you’d notice far less recoil and the ejection pattern may be closer to normal. If it’s not ejecting the brass at all, then you have your answer.

 

[PappyM3]

For anybody interested in checking their gas ports before they do a build (I understand this instance was a complete upper), pin gauges aren’t that expensive. This set will cover any gas port size, and also help you check other measurements like the gas key opening to make sure it’s in-spec.

https://www.amazon.com/gp/aw/d/B081TPPBZY?psc=1&ref=ppx_pop_mob_b_asin_title

Nope, just regular old preban 30 rounders. They worked fine in my Sig MCX.

Regardless of your situation, I would put these in your prebans, or other new springs like Wolff.
- https://sprinco.com/magsprings.html
- Enhanced Self-Leveling Follower™ – USGI 5.56x45, 3 Pack

Don’t need a second person for this. Is the brass trickling out right next to you? Going straight up? Behind you? Or taking a page out of the PTR 91’s book and launching it into next Tuesday?

The reason I ask, is that while many people think it’s under-gassed and short stroking, the symptoms of an over-gassed gun are similar. The brass can be the key. Over-gassed and you may have premature bolt unlocking which can jar the brass loose of the ejector and it just plops right next to the gun. It’ll also fail to strip the next round due to bolt speed, or it’ll cause a feeding malfunction and the round won’t chamber properly. Under-gassed can do the same thing but you’d notice far less recoil and the ejection pattern may be closer to normal. If it’s not ejecting the brass at all, then you have your answer.

Possibly, but I would be very surprised by that with .223 pressure ammo in a midlength gas system. That would be a honkin’ big gas port.

 

[pastera]

A quick estimate shows 22kpsi at a 0.063 gas port - should be plenty to cycle the action (and I have zero issues at 25.4gn with about 21kpsi

 

[DW357]

For anybody interested in checking their gas ports before they do a build (I understand this instance was a complete upper), pin gauges aren’t that expensive. This set will cover any gas port size, and also help you check other measurements like the gas key opening to make sure it’s in-spec.

https://www.amazon.com/gp/aw/d/B081TPPBZY?psc=1&ref=ppx_pop_mob_b_asin_title

Regardless of your situation, I would put these in your prebans, or other new springs like Wolff.
- https://sprinco.com/magsprings.html
- Enhanced Self-Leveling Follower™ – USGI 5.56x45, 3 Pack



Possibly, but I would be very surprised by that with .223 pressure ammo in a midlength gas system. That would be a honkin’ big gas port.

I've yet to need to replace the mag springs in any of my preban 20 and 30 rounders. However, the anti-tilt followers are a must.

 

[paul73]

For anybody interested in checking their gas ports before they do a build (I understand this instance was a complete upper), pin gauges aren’t that expensive. This set will cover any gas port size, and also help you check other measurements like the gas key opening to make sure it’s in-spec.

https://www.amazon.com/gp/aw/d/B081TPPBZY?psc=1&ref=ppx_pop_mob_b_asin_title

a set of cobalt drill bits may also serve well for that same purpose.
there is a small probability there for barrels - a shorter cut barrels can - theoretically - have gas ports made for suppressors. those are usually around 0.04 -0.06 in diameter.
normal port should be in 0.08-0.1.

 

[PappyM3]

I've yet to need to replace the mag springs in any of my preban 20 and 30 rounders. However, the anti-tilt followers are a must.

All depends on how much they’ve been used.

20 rounders don’t need follower changes and often don’t benefit from springs. Just the nature of the design. I still throw new Wolff springs in the 20 rounders to set my baseline though. I keep loose track of maintenance cycles.

 

[Alex9661]

I've yet to need to replace the mag springs in any of my preban 20 and 30 rounders. However, the anti-tilt followers are a must.

I've had a couple of 20 rounders that failed to lock bolt back. New springs cured it.

 

[Artie]

@Joeldiaz any update on your issue? Good luck

 

[Joeldiaz]

@Joeldiaz any update on your issue? Good luck

Yeah I changed out the standard spring with a reduced power Sprinco yellow one and it works fine now. I know it’s not the most reliable method but this rifle was an experiment and a range toy anyway. Later on I’ll consider working on the gas port to make it capable of accepting a standard spring, but for now I’m fine with the current setup.