WTF happened here? Pew go boom?

[Member 34319]

Something is off.

The lower's pin holes might be off. And the trigger, no matter which one is put in, is too low to allow the bolt to push the hammer down far enough to connect with the disconnector.

The bolt might be off and not pushing any trugger's hammer low enough to connect with the disconnector.

Could even be an upper tolerance issue.

Something isn't allowing the hammer to connect with the disconnector.

Does the hammer follow even when manually cycling the charging handle with the trigger pulled? Or is it only during firing the hammer doesn't disconnect?

 

[Member 34319]

Looking at the two bolts pictured, it's interesting the Aero has a ramped section. I'm curious if this is the reason the hammer on any trigger is not disconnecting. Might be a fatal flaw in their design. Just a little bit of extra tolerance and there isn't enough meat on the bolt to push the hammer down enough to disconnect.

 

[Hueco]

Something is off.

The lower's pin holes might be off. And the trigger, no matter which one is put in, is too low to allow the bolt to push the hammer down far enough to connect with the disconnector.

I really hope it's not the lower/upper. That's a bigger headache in getting it back to Aero and all...end of the day, I just want a working pew

Does the hammer follow even when manually cycling the charging handle with the trigger pulled? Or is it only during firing the hammer doesn't disconnect?

The weapon passes safety and function checks. I load up 5~10 snap caps and go through to check. The hammer resets just fine doing this - it's only during shooting that I have issues.

Looking at the two bolts pictured, it's interesting the Aero has a ramped section. I'm curious if this is the reason the hammer on any trigger is not disconnecting. Might be a fatal flaw in their design. Just a little bit of extra tolerance and there isn't enough meat on the bolt to push the hammer down enough to disconnect.

View attachment 1128626

This is primarily why I've gone lighter and lighter on the buffer...my thought being that the BCG wasn't moving far enough back and the hammer wasn't getting pushed past this ramp point. That doesn't seem to be the case, though...I've lightened the buffer assembly a lot to no change.

It may be a placebo effect, but I can feel the trigger resetting while slowly pulling the BCG back...this feels stiffer using the FZ over the Aero, which leads me to believe it's forcing the hammer down further. Could be wishful thinking, but it does seem to be more engaged on reset.

A quick and dirty caliper measure appears to show the ridge on the FZ being a few thousandths larger than that ridge on the Aero...I'll remeasure with a more accurate tool and post back. But, at this point, I'm thinking the Aero BCG may be out of spec.

@Cerberus Group - do you have a doc showing the spec measurements for the BCG? I want to say that the AR-9 BCGs should match AR-15.

 

[Hueco]

Looking at the two bolts pictured, it's interesting the Aero has a ramped section. I'm curious if this is the reason the hammer on any trigger is not disconnecting. Might be a fatal flaw in their design. Just a little bit of extra tolerance and there isn't enough meat on the bolt to push the hammer down enough to disconnect.

View attachment 1128626

I put both BCG's into the upper and measured from the bottom of the upper down to the flat ridge on each BCG (where the hammer would interface). The FZ is 0.012" taller than the Aero.

I'm thinking my BCG is off spec.

Do you have an EPC-9? Mind taking the same measure from your set up? I'm curious if it's the BCG, the upper, etc.

 

[Member 34319]

I put both BCG's into the upper and measured from the bottom of the upper down to the flat ridge on each BCG (where the hammer would interface). The FZ is 0.012" taller than the Aero.

I'm thinking my BCG is off spec.

Do you have an EPC-9? Mind taking the same measure from your set up? I'm curious if it's the BCG, the upper, etc.

.272" FM Products BCG and Aero EPC9 upper.

 

[Cerberus Group]

@Cerberus Group - do you have a doc showing the spec measurements for the BCG? I want to say that the AR-9 BCGs should match AR-15.

The AR-15 BCG is way different than a EPC 9mm BCG. I've built 2 EPCs for customers...so far haven't heard any problems coming back.

I've got a spare Aero EPC BCG to do some spec measuring if you need.

I used Rise Armament triggers in both customer builds, as they stated they are good to go for use in PCC's

 

[Hueco]

.272" FM Products BCG and Aero EPC9 upper.

Aero: ~.3175"


FZ: .301"


That's quite a ways from your measure. Hopefully this works

 

[arakboss]

I have read that to light of a buffer spring combo could allow the bolt to blow back to soon and cause case rupture type problems. This would be unrelated to trigger problems. Have you considered this?

 

[arakboss]

Could the timing be off for some reason such that the bolt begins its journey rearward before the bullet has left the case thereby exposing the case to rupture?

This is what I was thinking.

 

[arakboss]

I get bulged brass when shooting my 9mm PCC suppressed. Others have told me that it's common with suppressed and full auto. Was also having a failure to reset with a LaRue MBT at one time, but the problem hasn't returned. I didn't change anything except clean and lube.

Shooting suppressed would cause more back pressure. You could try a heavier buffer weight and see if that helps reduce the brass bulging.

 

[Member 34319]

Maybe measure a few 223/556 uppers to bolt as well?

 

[Hueco]

I have read that to light of a buffer spring combo could allow the bolt to blow back to soon and cause case rupture type problems. This would be unrelated to trigger problems. Have you considered this?

I'm not convinced this was it.

I got the case rupture / OOB when using a Sprinco Red + 7.7oz buffer.

Check back a few posts for my list of tests, but tldr; I've since gone all the way to regular carbine spring with 3oz buffer and haven't had another OOB.

 

[Hueco]

So, I sent Aero a message asking for spec measurements so that I could see if my stuff was out of spec.

No surprise to anyone, I didn't get them.

But, they did deduce that NONE of the triggers that I've used so far (Geissele, Timney, Rise) are approved for the EPC-9. They then sent back a short list of those that they say work. Here it is:

• Rise Armament BLITZ
• HiperFire PDI
• CMC PCC TRIGGER
• ELF SOCOM AR-9 Trigger
• ALG ACT

Now, I don't know why a Rise Armament RA-535 wouldn't work and a BLITZ would...but oh well. Aero won't go one step further with me until I try one of the above triggers.

The saga shall continue...

 

[Cerberus Group]

I've got Blitz in stock here...can send ya one if ya want it

 

[Member 34319]

So, I sent Aero a message asking for spec measurements so that I could see if my stuff was out of spec.

No surprise to anyone, I didn't get them.

But, they did deduce that NONE of the triggers that I've used so far (Geissele, Timney, Rise) are approved for the EPC-9. They then sent back a short list of those that they say work. Here it is:

• Rise Armament BLITZ
• HiperFire PDI
• CMC PCC TRIGGER
• ELF SOCOM AR-9 Trigger
• ALG ACT

Now, I don't know why a Rise Armament RA-535 wouldn't work and a BLITZ would...but oh well. Aero won't go one step further with me until I try one of the above triggers.

The saga shall continue...

Did Aero say these triggers are for compatibility with their bolt? Or was it compatibility with there upper/lower?

 

[Hueco]

Did Aero say these triggers are for compatibility with their bolt? Or was it compatibility with there upper/lower?

Didn't ask, didn't tell. Though I'm getting the distinct impression that they have tested their lower/upper with very few parts on the market.

I may have ripped on the poor support guy a bit for them not posting anything about the trigger on their website.

 

[Member 34319]

Didn't ask, didn't tell. Though I'm getting the distinct impression that they have tested their lower/upper with very few parts on the market.

I may have ripped on the poor support guy a bit for them not posting anything about the trigger on their website.

Just curious as you swapped the bolt and had issues. So if it's just those triggers that are approved for their bolt. Swapping bolts should make the list pointless.

I would think it's the bolt that requires those listed triggers, not the lower or upper type thing.

Hearing you say your issues repeated after swapping the bolt, raises concerns it's something else.

 

[3MTA3]

Didn't ask, didn't tell. Though I'm getting the distinct impression that they have tested their lower/upper with very few parts on the market.

I may have ripped on the poor support guy a bit for them not posting anything about the trigger on their website.

You were doing them a favor if common combinations of parts results in a full auto rifle. That represents a serious liability as well as unwanted attention from government agencies, special interest groups, and lawyers.

 

[Alexx1401]

You were doing them a favor if common combinations of parts results in a full auto rifle. That represents a serious liability as well as unwanted attention from government agencies, special interest groups, and lawyers.

I too am kind of shocked that they act like they really could care less about this. Seems like they are leaving themselves open to some real legal problems here.

 

[Hueco]

We have success, ladies and gents!

I happen to really like Triggertech, and have had an order in for their AR9 trigger throughout this saga. Well, it finally shipped and got to me, I finally installed it, and my AR-9 finally worked!

This is my second TT after an AR Diamond and what a fantastic trigger. Seriously.

But, since I've got all these triggers, here are some more measurements, for grins and giggles.

This is how high the hammer sits and where it catches the disconnect.


Triggertech: .543"
Rise: .354"
Timney: .339"

TTech:


Rise:


Timney:


And all three side by side:


The Rise definitely wins for style…but it's the TTech that has the hammer hit the disconnect much higher up than the other triggers. No BCG riding over the top and causing inadvertent auto fire.

So, now that the gun runs…time to perfect the recoil system.

I also have a Rise Blitz that should be delivered tomorrow that I'll take measurements of but which will be sold as new. All triggers except the TTech about to be listed in the classifieds - if you have been following this saga and wish to buy the Rise RA-535, Timney, or Rise Blitz, shoot me a PM.