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300BLK pistol. Failure to Eject.

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Hello.  I'm getting back into shooting and I ran into issues today.  May I ask for some troubleshooting advice?

 

Lower is a Radical Arms paired with a Radical Arms 8.5 inch upper in 300BLK.  The lower was purchased as a complete gun with a 10.5 inch upper in 223.  That functions well/reliably.  I am using the same gunfighter charging handle and the stock (what it came with) BCG.  The BCG looks to be of quality with MPI etched on, staked, etc. 

 

I used Remington green box 120 grainers from Walmart and some quite expensive Barnes TSX (also factory).  Magazine is a 20 round Magpul 2nd gen (no issues with other rifles/pistols)

 

The first 20 rounds seem to be fine; no failures.  After that - issues:  Round would fire.  Extractor will grab the case and attempt to pull it back.  Instead of flinging it out, it drops the spent case right on top of the magazine.  The BCG will push the new round in the magazine into the chamber but the spent casing is still on top of the other round and they both try to enter the Chamber.  It jams it up usually ruining one of the rounds.  

 

I attempted to fire it one round at a time.  It does lock the action back but again, not eject reliably.  

 

Any thoughts on what i can do to troubleshoot?  I did some googling.  Some recommended upgrading the extractor or putting an O ring but this BCG is brand new.  It also ejects the 223 rounds perfectly.  

 

 

 

 

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That would be my first guess, check that the extractor is clean and does not have any brass shavings in the extractor groove. Check your spent brass to see if the primer is backing out or not, then try the o-ring, and or new extractor.  

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Actually my first guess would be a weak ejector spring. It's extracting and gas system seems fine, (bolt locking back) but not kicking the rounds out, So I would check to see if the ejector is binding or bad spring.

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Ran into the same on my 300 Blackout with a 10" upper. This was with a brand new CMT BCG. Even tried the BCG out of my 16" 5.56 rifle and it did the same thing. Ended up putting the BCM Extractor upgrade kit in all my bolts and it fixed the problem. http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

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Ran into the same on my 300 Blackout with a 10" upper. This was with a brand new CMT BCG. Even tried the BCG out of my 16" 5.56 rifle and it did the same thing. Ended up putting the BCM Extractor upgrade kit in all my bolts and it fixed the problem. http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

 

I just bookmarked that. 

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Ran into the same on my 300 Blackout with a 10" upper. This was with a brand new CMT BCG. Even tried the BCG out of my 16" 5.56 rifle and it did the same thing. Ended up putting the BCM Extractor upgrade kit in all my bolts and it fixed the problem. http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

 

Hello Verne.  So i'm curious, does the action of the 300BLK differ from the 223/556 version where it needs a bit more "extracting"?

 

Thank you everyone for your help.  I'll plan to get the upgrade kit but I'm just curious now..

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When I was having issues I did a lot of searching on line trying to figure it out. Found a couple of threads over at www.300blktalk.com

If I remember correctly it has to do with the short barrel and the gas impulse having just enough force to pop it off the extractor but I have sleep since the so I could be wrong.

I had this issue with the two BCG I tried in my 300 blkout. After installing the BCM kits both worked perfect without any other changes.

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I had a similar problem with my 7.62x39 AR pistol. It would leave the spent round in the upper, and then wedge a live round up against it when the bolt came back forward. I always figured it was because the extractor spring wasn't strong enough to "bite" into the steel case ammo I was using. Sounds like our common denominator may be the .30 cal casings. Just a guess, but perhaps there is a difference in the way .30 casing expand vs the .223/5.56. For example, maybe the .30 cal casings expand their over all diameter more, where the .223/5.56 casings stretch and increase over all length. That line of thinking could be total garbage, but it's interesting that your pistol did the same thing with brass case ammo mine did with the steel case. My issues seem to have been remedied by a Wolf extractor spring. Time will tell, but with a 7.69x39 AR, I'm always waiting for my next malfunction. I wouldn't rely on that gun to save my life, but it's a blast to shoot. 

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These are not specifically for you but for anyone building an AR in 300 Blackout. Make sure to use a standard buffer, not a heavy buffer. Heavy buffers add felt recoil, especially on a gun that is already over gassed. I almost always recommend an adjustable gas block, especially if you are shooting anything other than subsonic ammunition or running a silencer.

A properly tuned AR is amazing.

It is very possible that your gun is overgassed when shooting supersonic ammunition with a pistol length gas system. The only way to fix it is to install an adjustable gas block. A heavy buffer can be used for troubleshooting but I would not leave it in the gun because it contributes to felt recoil.

Because it worked fine initially then quit I suspect something has worked loose. I would start by checking the gas key to make sure it is tight. Next I would verify the gas block is still tight.

If those look fine then I would install the fubber o-ring. You could also swap the bolt out with a known good one to see what happens.

It is not a gas issue of it worked previously.

We're any changes made to the gun?

Did the issues start happening with different ammunition?
.
It sounds like the ejector might be the issue then the extractor. Take a fired case and stick it under the extractor. Then straighten it out a few times to exercise the ejector. This is to make sure it is not bound up from crud.

If it still persists then I would look at the extractor. The extractor not only pulls the casing out of the chamber but also acts as the pivot point for the casing when it is being ejected. I would swap the extractor out with a known good gun to see it that is the issue. Some cheap extractors are not cut ax well as others and may not hold onto the casing strongly. At a bare minimum I would replace the spring and o-ring but honestly I would just install a completely new extractor.

I can PM my number and we can discuss further if you would like.

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Just for information, the 300 Blackout is no different than 5.56 below the shoulder. To make 300 Blackout from a 5.56/223 case you chop the 5.56/223 case at the shoulder.

Both supersonic 300 Blackout and 223 loads run at the same operating pressures as well.

Any 300 Blackout upper should run on any milspec 5.56 lower without modification. If a 300 Blackout upper will not work on a standard milspec lower then the problem is with the upper, not the lower. And if you MUST modify the firearm then modify the upper to work with the milspec lower and do not modify the lower to work with the upper.

I have been involved with the 300 Blackout for a very long time. I am a moderator on a board dedicated to the caliber. I have designed four bullets for use with the 300 Blackout and one is even being used in factory loaded ammunition.

I have probably seen every type of problem specific to the 300 Blackout.
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Dolomite knows Exactly what HE is Talking about with this Round for Sure, because He has been perfecting projectiles for this for a Really Long time! He has the recipe for this one for Sure! This is his Pet that He has been working with for a Long Long Time! He's Good...

I had the Same problem with a 300 BO a few years ago, Maybe 4 or 5?, and I was Baffled! Then after it happened the Very Last Time, it didn't eject the Brass but the BCG Tried to feed another Round into the chamber! Long Story Short, the Extractor Broke Off of the Bolt when it tried to Eject the Empty Case! I didn't Notice that the Extractor was missing for a few minutes, and I will say that if this Happens to you, take your Time and find the right Rods and tools to remove the Spent / Stuck Case from the Chamber. IT can be a Pain in the Rear!

I spoke to the person That orders the parts for their Company, HE said that the supplier that sells Extractors to them and a Lot of other Companies, had failed to Check the Hardness and made Sure they had Gotten the proper Heat Treat needed to Harden them to Mil Spe. He said that some would get a Stress Fracture then Break & other's were just to soft, and would cause more problems like I was having before they would break completely off. I wonder if somebody put those away several years ago and Decided to Break them out and sale them again?
I received a New Extractor Kit a few days later and installed it in a Bolt, and Everything Worked Great and Looked Great too because it was a different finish than my BCG and it looked Unique!!

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