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Posted: 2/23/2016 6:29:47 PM EDT
I recently completed an aero precision m5 build and am having feeding / chambering issues about every 7 rounds.
-Aero m5 upper / lower
-Ballistic advantage 20 barrel, rifle length gas with adjustable gas block
-kak dual ejector bcg
Tried three different types of ammo and frequently jams up chambering a new round.  Bolt locks back everytime on empty mag.  I'm using 10 round Pmags and with the bolt locked back it will get stuck as seen in the pic below hitting the bolt release sometimes and will randomly fail to chamber mid way through a mag as well, always hanging up like the pic below.  I took one of the o rings off and that didn't help.  The pic of the is what it looks like after it gets stuck
Could the dual ejectors be too much?
Any suggestions?
Kak and ballistic advantage responded within minutes to my email.  kak thinks it's a chamber / barrel issue.
Ballistic advantage offered to take a look at it if I send it in.
Very impressed with the customer service

Link Posted: 2/23/2016 6:39:03 PM EDT
Do you have a std. Bolt? Drop it in and see how it acts. Dual ejector might be to much.
Link Posted: 2/23/2016 10:50:49 PM EDT
[Last Edit: 2/24/2016 5:06:06 PM EDT by 1bigmag]
Wow, Ballistic immediately blamed my bcg, and as you would guess it wasn't one of theirs. They suggested trying another  BCG which luckily I know two people with one.  One is a hundred miles away and I work with the other. No one but them has suggested it's the bcg.  This is one time I hope their right and everyone including myself is wrong.  The bcg is warrantied and a lot easier to send off that trying to pull my Loctite 620 bedded barrel off.  Hope you get it running.
Link Posted: 2/24/2016 12:42:14 PM EDT
[Last Edit: 2/24/2016 12:43:10 PM EDT by LRRPF52]
Will factory ammunition drop into the chamber and fall out with gravity?

Before I assemble an upper, I test the chamber with the intended ammunition to ensure that it seats fully and drops free with gravity.

The barrel isn't going into the upper until that can be proven.

The marks on your brass look very strange, especially if a cartridge is being chambered in-line with the bore and comes out looking like that.

Does it do that only from when the cartridge feeds from the right side of the magazine?
Link Posted: 2/24/2016 9:30:04 PM EDT
did you check headspace?
Link Posted: 2/25/2016 12:44:24 AM EDT
headspace was checked and factory ammo will drop in and fall out with gravity

The mark on the brass is only on one side and after stripping the mag the charging handle is very hard to pull back to clear the jam.  
Not sure if this is occurring when the mag is feeding from the right or left.
Link Posted: 2/25/2016 1:34:05 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By redwoodm4:
headspace was checked and factory ammo will drop in and fall out with gravity

The mark on the brass is only on one side and after stripping the mag the charging handle is very hard to pull back to clear the jam.  
Not sure if this is occurring when the mag is feeding from the right or left.
View Quote

If it's from the right side of the mag, the problem is the ejectors impinging the case rim.

Erase the word "jam" from your vocabulary, except when referring to the crud between your toes and the stuff you smear on bread.

For firearms, we have different types of malfunctions.

Failure To Feed
Failure To Fire
Failure To Extract
Failure To Eject

Within each one of those, there are different possible reasons for the failure, which are either ammunition related, mechanical, or both.

Using the above terminology will really help us diagnose and suggest courses of action that will get your problem solved as quickly as possible, provided competent people are posting feedback and suggestions.
Link Posted: 2/25/2016 1:56:08 AM EDT
[Last Edit: 2/25/2016 2:04:50 AM EDT by 762AR556]
Open your gas block up all the way. Try with "full power" is what i like to think. The mark on the case looks strange indeed.

Possibly a tight chamber that swells with heat? The scrapes look like feed ramp marks, which could be receiver or barrel extension. That straight line across tells me to check the chamber. Or as LRRP said, if it's only from the right side, could be the ejectors not letting the round seat fully sometimes?

KAK makes good stuff from what I've seen and read. Haven't tried their stuff yet though. So i doubt the bcg is at fault here, I'd put the o-ring back.

I'm betting is a chamber issue, the reason BA would go to the bcg right away most of the time is there is a ton of bad ones out there causing issues. However, bad barrels make it through as well. I think that's the case here.

Tight, rough, or bad chamber altogether. And rough feed ramps on either the receiver or extension.

That's my guess at this point with the info so far. Id give it one more try on wide open gas if you haven't already. And clean the chamber really good. Oil as needed afterwards.

If it still screws up, then BA can't say anything about improper maintenance or care. You eliminate all possibilities first, then send it in cleaned and oiled, trust me when i say that's appreciated in any warranty work.

And a +1 on the proper terminology. They are all "jams", but caused by different things. So 99% of the time we need to know when the jam occurred. That's where the terms come into play.

I like this way:

Failure to chamber - FTC
Failure to fire - FTF
Failure to extract - FTX
Failure to eject - FTE

Makes senses huh?
Link Posted: 2/25/2016 10:05:26 PM EDT
[Last Edit: 2/25/2016 10:06:28 PM EDT by stooxie]
Thought I had a theory... scrapped it.


Link Posted: 2/26/2016 2:01:40 PM EDT
[Last Edit: 2/26/2016 2:02:53 PM EDT by js1977]
What buffer/ buffer spring are you using?  Had a similar issue with a PSA ar10,  was using all PSA, but bought the upper and lower separate.  I had changed out the buffer spring and buffer for a rifle (vs carbine) buffer/spring.  I had problems not being able to feed. I bought a different BCG with no luck.  I then took it to a local armor, they stated that it was a gas block issue/ head space issue and advised sending it back.  I sent the upper back only to have it continue to happen (PSA replace BCG) even though PSA had no issues.  I was pissed and finally started to investigate it myself.  Bought a true 308 buffer spring and another 308 buffer.  Rifle works flawlessly now.  Apparently my buffer/spring was too weak to force the BCG forward.  I'm not saying that yours is the same, but it's a cheaper avenue to check before going super crazy with buying BCG's only to find out the problem still exist.  Good luck.
Link Posted: 4/18/2016 10:19:29 PM EDT
Well it's been a while but figure I'll update you guys, sent the upper to Ballistic Advantage and they said they ran $15.00 in ammo through it with out issue with a different Bcg.  I'm assuming they cycled ammo through it unless they did a very detailed cleaning including the muzzle brake.   I then contacted kak and they told me to use there heaving buffer $55.00 and it should run fine.   Contacted Rainer arms and they said they would replace it even though it had been about 3 months.   They ended up sending me a replacement and low and behold this kak Bcg had two rounded ejectors, must be a redesign since there firsts one had issues.  I ended up buying an aero precision Bcg from Schuyler and it's been running great.   I'll probably sell the kak and avoid them in the future.  This was my first time using Rainer Arms and it will not be the last there customer service is awesome.
Link Posted: 4/19/2016 5:54:42 PM EDT
I've always stuck to using the same brand parts throughout the upper as much as possible, mainly to avoid tolerance stacking and the like. Another good part of it is that the manufacturer can't blame another part without still needing to verify it.

Pretty sure I would have had lots more issues getting some out of spec parts replaced from a supposedly-truly-precise manufacturer.
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