Help Troubleshoot a New Frontier AR9 Pistol

[doh31672]

So I had built a budget AR9 pistol, based on this lower https://www.newfrontierarmory.com/pr...-billet-lower/ (it was built before registration was required, serialized etc, so that isn't part of the question on the table).

Total budget build, so maybe I'm getting what I paid for. It's just a range toy, but would like to make it somewhat reliable. Took it to the range today and had the following issues. First couple mags, things worked well. Then I would find that after a shot, the hammer wouldn't reset. So I'd manually eject a round and then it would fire. After a while, it would happen every round. Once or twice, I would see the brass not eject from the ejection chamber.

It seems like there isn't enough power from the 9mm round to push the BCG back far enough to fully reset the hammer or eject the spent cartridge?

Couple other things which happened, which may or may not be related:

1. I had 2 double taps. I would load maybe 5-6 rounds at a time, and it never went full auto. The trigger kit is an ALG-ACT that was laying around in my parts bin.

2. The mag (an extended glock mag) seats pretty tight. To the point where it doesn't drop free when hitting mag release and actually takes some pressure to pull free.

Advice on where to start, to troubleshoot? My first thought was, get a weaker buffer spring? I could imagine that the inability of my BCG to push back far enough could relate to the misfire as well as the 2x tap. I could also imagine that I'm talking out my ***.

I'm also thinking about trying to remove a very small amount of metal from the mag well to let the mags move more easily. But I don't think that is causing my problem.

So suggestions or hypotheses welcome. Thanks

[plumbum]

I’d say buffer or spring change, or hotter ammo!

[Skip_Dog]

What buffer and spring you using?

Start there.

[doh31672]

I was running a milspec spring. I should have known better, given how much weaker the pistol caliber round is. Will start there.

I do have an extended 9mm bcg. So at least that's one less variable.

Thanks

[naz]

Hello, what is the bolt and buffer that you are using? Are rounds being stripped from the magazine and fed properly but the trigger does not reset?

I had a similar situation (new frontier gen 2 billet lower, Taccom upper/bolt/buffer) with intermittent double fire and no reset issue when I used Geissele Sd3g trigger and I resolved it by switching to Hiperfire X2S mod 3 trigger.

Edit: there are some posts that suggest that the 9mm AR style pcc need heavier buffer and stronger spring. So I wouldn’t assume the issue is that you need a weaker spring. I don’t know the weight of the Taccom spring but it takes more hand force to rack the ch and the buffer is 6.2oz.

It might be worth it for you to get a matched buffer system and bolt, if the trigger change doesn’t work out

[Quiet]

So I had built a budget AR9 pistol, based on this lower https://www.newfrontierarmory.com/pr...-billet-lower/ (it was built before registration was required, serialized etc, so that isn't part of the question on the table).

FYI.
If it wasn't serialized and voluntarily registered before 07-01-2018 [PC 29181(c)] or registered and serialzed with CA DOJ info before 01-01-2019 [PC 29180(c)], then, starting 01-01-2019, it is considered an illegal self-made firearm. Which means it is subject to confiscation/destruction [PC 29180(d)(3)] as evidence of violating CA self-made firearm laws.

[enorbit3]

Typically an ar9 will use a stiffer spring, not a lighter one. What buffer and big are you using?

I run a jp .308 spring, spikes 9mm buffer, and a faxon bcg on mine. No issues. I'm also using an alg qms trigger.

[hitdank]

He has a pistol so the shorter barrel might require softer spring. We always talk about rifles with solid 16s.

[naz]

He has a pistol so the shorter barrel might require softer spring. We always talk about rifles with solid 16s.

My pcc has 10” threaded barrel and 6” pin and weld shroud and it uses heavier spring and heavier buffer than AR15 carbine.

Do you have a AR style pcc? What is your setup

[sigstroker]

There's a chance just the opposite of what you think is happening is what's really happening. It could be the bolt speed is so high that the hammer is bouncing off of the disconnector and the sear can't catch it. The hammer follows the bolt and is uncocked. It's common with 9mm AR's. Do you have a 9mm buffer? They are heavier and longer than a regular buffer.

[JTROKS]

Are you using Glock extended mags?

What brand ammo are you using?

[hermosabeach]

Where is the brass landing? 1 o’clock to 6 o’clock
How far is the brass from the firearm when sitting?

You have a bucket or parts... it’s difficult to diagnose when we don’t have a known starting point.

— what exactly is happening?
The gun fires and then???
Empty brass is still in chamber?
Empty brass is high? Type 2 malfunction
Double feed of new cartridge and empty brass?
Is the trigger dead but a new round was chambered? Hammer followed bolt forward?

Are these Glock magazine or some off brand Glock Korean jam magazine?

If aftermarket mag- have you tried an OEM Glock magazine?
It seems like there isn't enough power from the 9mm round to push the BCG back far enough to fully reset the hammer or eject the spent cartridge?

[BigPimping]

Just like the previous posters. I would say buffer, spring would be the first thing. Then I would try maybe some hotter ammunition. Maybe some plus p loads.

[doh31672]

So I think, as expected, I don't know jack. I should have done a more thorough review of my setup before coming to the boards and flaunting ignorance.

I have an Vltor A5 pistol buffer tube and a Kaw Valley 10 oz pcc (extended) buffer.

I think the culprit is the spring. When I measured the buffer spring (which came with the vltor from a different AR pistol setup) it measured about 9.5" (and it doesn't look the spring was cut and didn't think it was so worn down that it would be compressed by over .5"). Plus I read that these vltor tubes are meant to run rifle length springs.

So I'll try it with a milspec spring and will get a rifle spring to check out next time i can get time at the range.

Thx all.

There's a chance just the opposite of what you think is happening is what's really happening. It could be the bolt speed is so high that the hammer is bouncing off of the disconnector and the sear can't catch it. The hammer follows the bolt and is uncocked. It's common with 9mm AR's. Do you have a 9mm buffer? They are heavier and longer than a regular buffer.

[Burken01]