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Franklin0722

Gibbz g10 308 build problems

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Franklin, I am having the exact same issue. I am so frustrated with my Gibbz 308 build. I spent a lot of time and money on it and it isn't functioning properly. I have spoken to Gibbz and they recommend that I ship them the rifle for inspection. Hearing that they took your upper for several months and then returned it to you in the same condition makes my heart sink. 

My saga so far: I put together the build in early June. Gibbz G10 upper with ballistic advantage barrel and ballistic advantage bcg. Gibbz G10 lower with CMMG LPK, Geissele ssa e trigger, Luth AR stock. 

On first range trip out rifle wouldn't cycle properly. It will barely poop out the empty brass, but fail to load another round. Bang, click. Won't hold open on an empty mag either. Also sometimes when cycling a round, either manually or when firing, a round will just fail to feed, getting hung up on the barrel extension. Tried several range trips, lots of lube, ammo types. All the same. 

At first I blamed the gas system. So I had a new gas block and tube installed and put in a JP recoilless buffer. Still acting exactly the same. So clearly it isn't the gas system.

It seems like there is just something off with the geometry that causes the bcg to slow down and cause feeding problems. I noticed some unusual marring on the bcg that leads me to think the bcg is riding on the side charging handle, causing it to lose velocity and not donits job. 

But what do I know. Im not a gunsmith. Maybe their upper receivers are just out of spec. I believe someone did say they used a Gibbz G10 lower with a different upper, correct? 

I am already afraid that Gibbz won't be able to fix the problem and when I do get the rifle back in several months it still won't work, and I'll end up having to tear the thing apart and buy a different receiver set and rebuild it. Ugggggh.

Please keep us posted Franklin. I am very eager to hear what Gibbz does on the second go round. I so wish I had just bought a freaking M1A at this point. 

 

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On 1/18/2020 at 4:44 PM, 98Z5V said:

This is the FOURTH confirmed problem we've seen with the Gibbz platform here.  This is #4.

Here is the Gibbz history here.  There have been no resolutions or fixes found, as far as I know.

https://forum.308ar.com/search/?q=Gibbz

Hey 98Z5V,

 

I followed this link and didn't see any other threads about Gibbz G10 issues. Did some searching of my own and o ly found this one. Can you help link me to the other threads on this topic? Id really like to read them because I'm having the same issue. 

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1 hour ago, SacramentoGunGuy said:

Hey 98Z5V,

 

I followed this link and didn't see any other threads about Gibbz G10 issues. Did some searching of my own and o ly found this one. Can you help link me to the other threads on this topic? Id really like to read them because I'm having the same issue. 

You, now, are Number 5, here.  If I've identified 4 previous, here, then it should be pretty obvious on the search terms.  The link in my last post was a clue.  That got by you, somehow.  At any rate, here is the search history of that platform, here on this board.  Happy reading.

https://forum.308ar.com/search/?q=Gibbz

Sorry about your luck, too - wish you'd researched it before you bought it.  At this point, we can only start another tech thread, try to figure out what's fucked up -and try to fix it for you.  From the previous threads - I don't think we identified the real issue. 

It's not a good design, I think is what we came up with.  researching those previous threads I linked - that's a starting point. 

Sucks to be so glum about it - but that platform never performed - and I haven't seen anyone else come back in here - with proof - to show that it worked.  You might be that guy, though...  :thumbup:

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On 8/13/2020 at 11:33 PM, 98Z5V said:

Hope that link helps...   :thumbup:

Hey 98z5v, I have an update and also a question. 

 

So I sent the rifle to Gibbz. They drilled out the gas port, said it was running fine, and sent it back. When I went to fire it, the short stroking problem was resolved, but now I have a new problem. Well, I had experienced this problem intermittently before, but I attributed it to the short stroking. 

The problem is a jam that I will try to explain. The round starts to go into battery, but is being presented at too steep of an angle so the bullet wedges against the chamber wall. Once the forward motion of the round is halted, and the round is at an awkward angle, the back of the case is pushed downward by the bolt as it travels forward until the bolt is riding on top of the case. The bolt then impacts the case a little below the shoulder. Ill post a pic that shows the end result. 

I can reproduce this jam when cycling by hand, so it isnt the gas system or the buffer. It seems to me the geometry of the feeding is off and after some research I think I figured out why. 

The barrel extension has M4 feed ramps that aren't blended into the upper receiver. Not only that, but when you look at the correct angle, you can see a ledge of aluminum where the bullet is supposed to meet the feed ramp. Seems to me, if this were smoothed out and blended, the feeding issue would likely resolve. Ill post a pic of the feed ramp too. 

What do you think? 

20200913_212811.jpg

20200913_212319.jpg

20200913_230913.jpg

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Do you still have the JP buffer system in the gun? If so go back to the rifle buffer and spring you first used. What you are seeing could be caused by the bolt traveli g to fast. The original rifle buffer and spring will slow that down and give the magazine time to raise the round all the way.

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Thanks for weighing in! I dont mean to be dismissive, but given that I can duplicate the jam by working the bolt by hand slowly, I don't think its a matter of the bolt traveling too fast.

 

I'm thinking either I need to cut some feed ramps into the upper receiver, or one of the receivers is just out of spec and the rounds are presenting too low. 

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I’d hit the receiver with a file or dremel and get a smooth transition to the barrel extension feed ramps and try it again. Original design didn’t have ramps but I don’t like not having smooth look. When you cycle by hand are you getting the bolt all the way back? If you release from bolt catch does it work? Is the bolt catching enough of the base to strip the round? Is the mag full? Try it with just a couple rounds. Try a diff mag.

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9 hours ago, SacramentoGunGuy said:

Thanks for weighing in! I dont mean to be dismissive, but given that I can duplicate the jam by working the bolt by hand slowly, I don't think its a matter of the bolt traveling too fast.

 

I'm thinking either I need to cut some feed ramps into the upper receiver, or one of the receivers is just out of spec and the rounds are presenting too low. 

These systems are not designed to be worked by hand slowly.

If you do a search here. You will see that almost everyone that has some type of fancy buffer/spring has feeding and cycling problems till they take those parts out and replace them with tried and true setups.

The dremmil bits for sharpening chainsaws work well for extending the feed ramps on the upper.

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19 hours ago, SacramentoGunGuy said:

here's another pic showing the feed ramps straight on 

20200913_224701.jpg

Dremel with the Chainsaw Sharpening Bit will knock that aluminum out of the receiver real quick.  It'll match/blend that upper to the feed ramps very well.  Don't worry about the steel feed ramps so much - the aluminum from the receiver will go, long before you hurt those steel feed ramps.  :thumbup:

ALSO...  That's the right round, out of a double-stack mag that's jammed, in these pics - is it always a right-side round that jams?...  Take a pic of your ejector and post it up.  Need to see what that ejector looks like in the bolt face...  

Edited by 98Z5V

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49 minutes ago, 98Z5V said:

Dremel with the Chainsaw Sharpening Bit will knock that aluminum out of the receiver real quick.  It'll match/blend that upper to the feed ramps very well.  Don't worry about the steel feed ramps so much - the aluminum from the receiver will go, long before you hurt those steel feed ramps.  :thumbup:

ALSO...  That's the right round, out of a double-stack mag that's jammed, in these pics - is it always a right-side round that jams?...  Take a pic of your ejector and post it up.  Need to see what that ejector looks like in the bolt face...  

98Z5V would that be the 5/32" or the 3/16"? that seems to work best?   I have both sizes.

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Just now, mrmackc said:

98Z5V would that be the 5/32" or the 3/16"? that seems to work best?   I have both sizes.

They'll both work, Mack.  5/32" is easier to use to blend, because it's smaller, but they both work well.  :thumbup:

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