BattleRife
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Does it lock back after the last round is fired? If so, it isn't short stroking.
What causes this malfunction? Failure to eject. Pictures
- Thread starter Roddy
- Start date
Greenhorse six I am using G96. Lots of it.
So I swapped the bolt from the Norinco BCG that would t go forward with the bolt in it now and the problem did not get any better. I am having about the same failure rate. The brass is moving about six or seven feet.
One weird thing, when the bolt held open on my last round of a LAR mag the casing was halfway out of the chamber. I don't think two differant extractors ad ejectors would be faulty would they? Makes me think its something else like the gas tube or buffer but I don't know.
There is another weird one.
Slinky I have some 75gr I will try next time. So far I have tried PMC Bronze and Norinco. Neither is better than the other.
So I swapped the bolt from the Norinco BCG that would t go forward with the bolt in it now and the problem did not get any better. I am having about the same failure rate. The brass is moving about six or seven feet.
One weird thing, when the bolt held open on my last round of a LAR mag the casing was halfway out of the chamber. I don't think two differant extractors ad ejectors would be faulty would they? Makes me think its something else like the gas tube or buffer but I don't know.
There is another weird one.
Slinky I have some 75gr I will try next time. So far I have tried PMC Bronze and Norinco. Neither is better than the other.
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I got a pretty new norc 14.5 which I experienced the problem in the first picture a few times. I noticed that it only happened with Pmags. So now I am pretty liberal with wetting the bolt. Also got the spike st 2 buffer, a cs buffer spring, another extractor and extractor spring, all from brownells (which is fantastic with the shipping only $12 for everything). I'll see if it happens again. I noticed with the mods now the rounds don't get ejected as far.
I have tried LAR mags, XCR mags, and D&H mags and I may have used Pmags. I may try a differant buffer and spring but the rounds eject quite well when they eject so maybe that isn't it?
Thank you very much to everyone for all your help and ideas. It is very much appreciated. This wouldn't big me so much if the gun wasn't just a blast to shoot. It's one of my favourite rifles for plinking.
Thank you very much to everyone for all your help and ideas. It is very much appreciated. This wouldn't big me so much if the gun wasn't just a blast to shoot. It's one of my favourite rifles for plinking.
Humm, different bolt, same problem. How is the rim on the spent casings? Are they chewed up? Take a spent case and drop it into the breach. Release the bolt. Can you pull back on the charging handle easily to extract the case or next time at the range, with the rifle pointing downrange, insert a mag into your rifle with a round in it, release the bolt and see if you can easily pull back the charging handle to extract the ammo?
If yes. Does the shell extract away from the rifle cleanly or does it just dribble out? If dribble out, check and see if there is good spring pressure on the plunger in the bolt face. Then again, you said the shells extract cleanly when manually extracted. Hummmm
Another possible reason could me misaligned gas port/gas block or fouling in the gas tube? Do you use WipeOut? If so, spray some down the gas tube and see if it foams out the other end by the gas block. Then again, you did say the bolt locks back on an empty mag.
How are the gas rings on the bolts? Have you checked to ensure they're not worn ie, if you extend them outwards from the BC and stand it on the bolt face, does it support the weight of the BC or does the bolt slip easily backwards into the BC?
The other problem could be that the timing is off ie the bolt is cycling slower than it can extract the spent case while the fresh round is already on the way up from the mag, lifting the spent shell and preventing it from extracting? Did you change the buffer to a heavier one or changed out the buffer spring prior to having these problems? Is the buffer tube loose?
I'm just grasping at straws. You might need to have a smith or a buddy who knows his AR platform to have a look at it.
If yes. Does the shell extract away from the rifle cleanly or does it just dribble out? If dribble out, check and see if there is good spring pressure on the plunger in the bolt face. Then again, you said the shells extract cleanly when manually extracted. Hummmm
Another possible reason could me misaligned gas port/gas block or fouling in the gas tube? Do you use WipeOut? If so, spray some down the gas tube and see if it foams out the other end by the gas block. Then again, you did say the bolt locks back on an empty mag.
How are the gas rings on the bolts? Have you checked to ensure they're not worn ie, if you extend them outwards from the BC and stand it on the bolt face, does it support the weight of the BC or does the bolt slip easily backwards into the BC?
The other problem could be that the timing is off ie the bolt is cycling slower than it can extract the spent case while the fresh round is already on the way up from the mag, lifting the spent shell and preventing it from extracting? Did you change the buffer to a heavier one or changed out the buffer spring prior to having these problems? Is the buffer tube loose?
I'm just grasping at straws. You might need to have a smith or a buddy who knows his AR platform to have a look at it.
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Bolt holds open on last round fired, so it is not undergassed. (unless it's an intermittent problem and you were just lucky on all five "last round fired" tests, but that's pretty unlikely)
You've clearly got an extraction problem. Gas, BCG, and buffer/spring are involved. enefgeee's comment on balance being especially critical for short guns is spot-on. Boss351's comment loose buffer tube nuts is worth checking, too, since it would be a quick easy fix.
Short guns tend to have overgassing problems, so that's where my money would be. Exacerbated by using hot Norinco ammunition. Too much gas too early gets the bolt carrier moving rearward before the fired case has shrunk down from peak firing pressure, so it is stuck firmly in the chamber. The extractor can't completely overcome the friction holding the still-expanded case in the chamber, so it doesn't get it completely extracted before the extractor hook jumps off of the rim. Results in apparent "double feed" due to too much gas (not a "real" double feed).
I'd say try a heavy buffer and heavy spring for the most mechanically correct solution to the overgassing problem. Extra power extractor spring would probably help, too, but that's probably not the root of the issue. (a weak extractor should work just fine IF the timing and gas are both correct)
If you want to confirm the overgas condition before trying the heavy buffer, try using some known low-power 223 ammo. I think cheap Remington supposedly fits the bill (but I never use the stuff). Using lower pressure ammo should reduce the frequency of the problem (but not eliminate it).
You've clearly got an extraction problem. Gas, BCG, and buffer/spring are involved. enefgeee's comment on balance being especially critical for short guns is spot-on. Boss351's comment loose buffer tube nuts is worth checking, too, since it would be a quick easy fix.
Short guns tend to have overgassing problems, so that's where my money would be. Exacerbated by using hot Norinco ammunition. Too much gas too early gets the bolt carrier moving rearward before the fired case has shrunk down from peak firing pressure, so it is stuck firmly in the chamber. The extractor can't completely overcome the friction holding the still-expanded case in the chamber, so it doesn't get it completely extracted before the extractor hook jumps off of the rim. Results in apparent "double feed" due to too much gas (not a "real" double feed).
I'd say try a heavy buffer and heavy spring for the most mechanically correct solution to the overgassing problem. Extra power extractor spring would probably help, too, but that's probably not the root of the issue. (a weak extractor should work just fine IF the timing and gas are both correct)
If you want to confirm the overgas condition before trying the heavy buffer, try using some known low-power 223 ammo. I think cheap Remington supposedly fits the bill (but I never use the stuff). Using lower pressure ammo should reduce the frequency of the problem (but not eliminate it).
Replace the ejector spring - and really clean out the ejector hole, clean and replace the extractor spring, and insert with a decent quality spring and insert. It's possible that the ejector is sometimes sticking back in it's hole and not forcing the case out. Look for burrs and rough edges where the cut outs are machined for the ejector and extractor. Check that both parts move freely as they should in their respective locations.
arcticcathonda
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H2 or H3 i would think
You might want to confirm that overgassing is definitely the problem before shelling out for a variety of heavy buffers. Check function with low power ammunition, and a detailed photo of the brass can help tell (brass would be dinged up around the base).
By changing the buffer weight, you won't actually be changing the gas situation, you'll just be helping to reduce the effect. There's no way to tell just how heavy a buffer you can run until you try it. As arcticcathonda says, try a 4 or 5 oz buffer. Any heavy spring should also help the situation, but less so than increasing the buffer weight will. As your buffer and spring weight increase, at some point you will have insufficient gas to completely cycle, and then you should dial it back down.
Before you do any of that, make sure that your receiver extension tube is solidly attached.
If you're doing this type of experimentation, then there is really no reason why you shouldn't also install a heavy extractor spring as suggested above. There is no disadvantage to using a heavy extractor spring (and they're very cheap).
Here is Mike Pannone's argument for using the heaviest buffer and spring that your rifle/ammo combination permits:
w ww.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/
arcticcathonda
CGN frequent flyer
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- Southern Alberta
REALLY!? Care to elaborate.
I should have worded that much better.
If the gas pressure is too high as a result of too large of a gas port, changing the buffers will have little to no effect on the end result.
The OP should continue to investigate the source of the problem before buying and replacing components.
That's not my understanding of the effect of overgassing on the extraction cycle (post 28). What's your understanding?
Regardless, as I said above, I agree that more time spent diagnosing the problem is advised.
Well I should have been more careful how I worded things.
The first question is, has this rifle had this problem since new, or did it crop up?
If you were to cycle the action manually, how is the ejection pattern?
As you increase the reciprocating mass the more effect it has on the acceleration of the bolt carrier. Remember that the bolt carrier is only powered for a short distance and the remainder of the travel is momentum. There will be a point where there is too much energy being transfered to the bolt carrier that additional mass alone will not have enough of an effect.
First you need to identity the source of the problem. It is possible changes to the buffer/bolt carrier could fix it but figure out whats wrong instead of just replacing stuff.
