Failure to extract, stovepipe, weak ejection

[redtornado23 0]

so i was at the range with my AR yesterday and was having problems with some failure to eject and stove piping and my buddy mentioned that it looked like my brass wasn't being ejected with as much force as it should.  in thinking about the problem google brought me to this video:  http://www.youtube.com/watch?v=fuCinEiYuIQ  and listening to this guy talk, he was having the same exact problems, which were solved by a new H buffer and spring....understandably becuase his spring was 9 years old.

 

the ar i'm talking about is maybe 8 months old and has about 2000 rounds through it.  16" barrel, mid length gas system, spike's milspec buffer tube, spring and T2 buffer.  so i'm pretty sure nothing is worn out.

 

i was originally thinking maybe i'm running too heavy a buffer?  Spike's T2 is 4.1oz compared with an H at 3.8oz or standard which is 3.0oz.  But now i'm thinking maybe it's not a buffer issue, i might need to be running a stiffer spring?

 

what the guy in the video describes is exactly what i experienced, spent cartridge not being removed while a new round is trying to be chambered.  I'm thinking a stiffer spring would slow down the bolt and give the chamber pressure time to relieve itself so the extractor can pull the spent cartridge out...

 

this is turning into a novel.  it's an easy enough thing to try, i'm just looking for some thoughts or other things i might check...?

[MidwestPX 172]

This sounds like a gas issue. What brand of ammo and is was it your first time shooting that? Have you disassembled the BCG and reassembled it prior to the visit to the range?

[Vlad G 345]

I agree, it sounds like the gun was running under gassed. That can be because of many things, weak ammo, undersized gas port, shifted gas block, or a really dirty bolt/carrier.  If the gun ran before, the recoil system hasn't changed and it is unlikely to have worn given the age of the rifle.

[redtornado23 0]

The ammo i was using was Federal American Eagle 5.56x45 XM855 62grn, which i have shot before.  Out of the 100 or so shots i fired (i was in the process of zeroing irons and a new red dot) i had maybe 3 failure to eject and 2 stove pipes. I've had a a couple of the same issues come up before, maybe 1 in a 100...but yesterday it was extremely annoying.

 

Prior to this trip the gun was broken down and given a cleaning, i diassembled the BCG, cleaned, lubed, etc.  I haven't broken anything down (yet) since yesterday but of course i want to take a look at things.

 

Gas issue...which means you think the rifle is under gassed?  The rifle has never had issue locking the bolt back...but the weak extraction has me thinking maybe?  I'm also running a heavier buffer than standard...i'm thinking it might be something as simple as changing to a standard weight buffer.

[Vlad G 345]

If you had problems before, then go to a lighter buffer and see what happens.

 

The heavy buffers aren't really needed for most people.

[High Exposure 5,664]

What are the rest of the specs on the rifle?

 

Is this a built gun or a complete rifle?

 

Complete upper or built upper?

 

Who makes the BCG?

 

What barrel, gas tube, and gas block, are you using?

 

What length is the receiver extension - carbine or rifle?

 

Is the stock pinned and if so, is it pinned correctly?

 

Is the action spring or buffer rubbing on anything in the receiver extension?

 

I agree with MWPX, it sounds like a gas problem and that is what I would focus my attention on - after I swap in a standard action spring and a standard buffer and see if that solves any issues. Another thing to try would be to swap lowers with another AR that I know works.

 

If nothing changes I would continue to use the standard parts while running ANY diagnostics. Having too many non-standard parts make it tough to track down the true source of any issues you may be having.

 

The test to determine if a rifle is undergassed is to put one round into a mag, load, fire and see if it locks back on the empty mag. If it won't lock back on an empty mag that is a sign of an undergassed system*

 

If it fails that test I would check the BCG first - in my experience a loose carrier key is the primary culprit for gas issues. Again, as a quick test I would swap BCGs with another AR that I know runs well and see what happens.

 

If that doesn't solve the issues I would check the rat of the gas system, one component at a time.

 

 

*being undergassed is not the only thing that can cause this issue but it is the most common reason.

[Respect2A 0]

Let's not forget he said he didn't really have any problems, then he broke it down to clean it, then had problems after reassembly.

[redtornado23 0]

self built upper and lower using spikes upper, lower, bcg, carbine length milspec buffer tube, spring and ST-T2 buffer. bcm 16" midlength barrel, gas tube and yhm railed gas block non-adjustable, fixed magpul stock.

 

i still need to take down the gun and see of anything is rubbing or looks funny.

 

the rifle will always lock back on an empty mag.

 

respect2A - true, but i was also running ammo i don't typically shoot.  i'd like to not touch or change a thing other than to verify nothing is rubbing or broken and see if the rifle will run fine on the usual pmc or wolf ammo i use.

[redtornado23 0]

so i took the rifle down. everything seemed to be working exactly as it should.  everything was still lubed well, nothing rubbing, hanging up, etc.  i will say this...i've heard steel cased ammo runs dirty, i shoot wolf all the time - this federal stuff was even worse.

 

i took apart the bcg, checked rings, gas key, etc.  everything looks fine.  i really want to run some different ammo and see what happens.  that being said, i'd really like to be able to use any kind of ammo and have the gun run without any problems.

 

i need to grab my buddy so we can swap lowers and see if that provides any clues.  looks like its time to buy ammo...

 

thanks to everyone for the comments so far.

[MidwestPX 172]

I may know what your problem is. If you normally run steel cased Wolf, your chamber is likely really dirty. This is because steel doesn't expand the same way brass does. Brass expands in the chamber to seal it and then snaps back to size due to its elastic nature. My guess would be due to the Wolf, your brass is expanding and sticking due to the soot and junk lining it from previous rounds. This is creating enough friction to mimic short stroking. People rarely have issues shooting steel case ammo unless their extractor was cast or they switch to brass cased ammo.

[JackDaWack 2,895]

http://www.amazon.com/Otis-Technology-FG-367-TP-Chamber-Brush/dp/B000E59A8E/ref=sr_1_1?ie=UTF8&qid=1400352720&sr=8-1&keywords=chamber+brush+223

[Lalo 13]

I may know what your problem is. If you normally run steel cased Wolf, your chamber is likely really dirty. This is because steel doesn't expand the same way brass does. Brass expands in the chamber to seal it and then snaps back to size due to its elastic nature. My guess would be due to the Wolf, your brass is expanding and sticking due to the soot and junk lining it from previous rounds. This is creating enough friction to mimic short stroking. People rarely have issues shooting steel case ammo unless their extractor was cast or they switch to brass cased ammo.

+1

 

When was the last time you used a chamber brush and really cleaned the chamber well? After you clean it use a mop or patches and make sure the chamber is clean of any solvents and dry before you shoot anything again.

[redtornado23 0]

sorry guys but no, the gun was extensively cleaned prior to this trip to the range.  i have a both a chamber brush and mop that were both used as part of the cleaning.  i hadn't cleaned after the previous trip and knew my next range day would be for sighting in so believe me when i say the gun was spotless.  i was almost thinking maybe i had let too much clp or lube get into the chamber somehow and that was causing the catridges to stick...but i'm not sure A. that that happeend or B. that things would stick because of that.

[redtornado23 0]

so in researching the issues with my rifle, i came to the conclusion that it was over gassed, and the bcg was trying to pull the spent cartridge out of the chamber too soon, before the chamber pressure was relieved enough to allow for this to happen, causing the spent cartridge to remain the chamber while the bcg cycled and attempted to load another round.  or, the bolt would pull the spent cartridge out with resistance and slow the bcg enough so that the ejected cartridges came out "weak"

 

everyone says that steel case ammo does not expand like brass, so the fact that my rifle would run steel with no issues, is most likely because of exactly that - the cartridge would not expand or seal as tightly as brass, therefore my bcg could remove the spent cartridge with no issues, while the the minute i tried to shoot brass, i would see extraction problems.  add on top of that...most steel cased ammo is "weak" it is not the same as shooting better quality brass or match grade ammo and by quality i mean "bang" - less chamber pressure equals less to overcome and easier extraction.

 

so i needed to slow my bcg down, and since i do not have an adjustable gas block and i felt it was much easier and cheaper to play with buffers and springs.  so in went a blue Sprinco enhanced power buffer spring and a "real" H2 buffer (the Spikes T2 i was using is weighted a half ounce or so less than an H2) and at the same time i swapped out my stock extractor and ejector springs for Tubbs chrome silicon springs.

 

i then labeled five mags with varying ammo, 62g xtac, 55g xtac, 62g federal, 62g wolf and 55g wolf and set out for the range.  i fired 10 rounds of each, in varying orders, five times.  i did not have one fte, ftf, jam...not one problem, and the bolt would lock back on an empty mag every time.  if i would have had a coffee can next to me i would have dropped every ejected case into that can, extraction seemed to be between 3 and 4 o'clock

 

after the first pass i could tell without looking which ammo i was shooting, the difference in recoil/power between the different brands/types of ammo was noticeable.  i for one will never shoot 55g wolf again, it's pretty weak stuff.

 

i just thought i'd put some closure to this and put this out there for anyone else who might be having the same problems.

 

thanks to everyone for their feedback