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New here, lots of long guns and short guns but first ar10. Started with an Anderson AM10, refitted the floating guard and dremmeled quit a bit of material off the bolt catch before it would engage the bolt and lock it back, my impression of the rifle is overall good machining but poor fitting. Added a nice scope, trigger, and brake, shoots close to 2 in at 200 yards with misc headstamp twice fired brass loaded on my dillon 650, only problem is 1 in 10 ejected shell turns sideways case mouth out and jams on the fresh round. Tried more and less powder, different powders, different bullet and weight, same results. Tried new starline brass. Tried factory ammo. Sometimes 20 rounds, sometimes 3. What 's next to try? 

20180708_102817.jpg

20180708_102902.jpg

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Gassing would be the next issue, if those two are good. Over-gassed is my strongest suggestion, based on the pics. Wrong recoil system would be a close runner-up.  You've given only basic information on the parts in this build, and so much more is required.

What you have to ask yourself is this - how did this piece of brass that stuck in there get a dented case mouth, AND get stuck like that?  I don't know...  That happens on ejection, when the brass tags the shell deflector.  Usually.

image.png.438416e2e5b05b6a899694550e40baa4.png

Edited by 98Z5V

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It's all about the bolt travel, I think it explains both issues; why you couldn't get bolt lock back, and why the bolt is overrunning the cartridge in the mag and catching the spent brass. The bolt simply doesn't travel far enough to the rear to catch the rear of the next cartridge.

You may have an out of spec bolt carrier group, recoil buffer and/or action spring, and/or buffer tube. Maybe even all the above.

I suspect your recoil buffer/spring/tube are the source of your issues, and that once you get that to spec you can go back to an unmodified bolt catch.

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In all our years, I can’t recall a bolt catch that needed to be drastically resized. You either have the wrong buffer or wrong buffer tube. 

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6 hours ago, Albroswift said:

where would I find the spec on the groove width/ depth/ placement?

That is what makes this forum the great place it is, no cut and dry "specs" on the big frame. Boils down to trouble shooting by the experts to decipher what parts are not playing well with the system. There is a wealth of knowledge here from members and in the threads. Give the guys some info like a parts list and measurements on the buffer system and odds are something will stand out right away. 

Welcome from Iowa, via N.C.

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Hello, Matt 

It is running back plenty far, it chambers the next round and then jambs the spent round on top of it. 

The photo is simulated, I thought after I was done shooting a photo would be easier then trying to explain so I staged it, I'll look at the case mouth next time. All the other case mouths of the ejected brass have that little dent, similar to my BAR. 

Hello, Robo

The bolt catch would not rotate on the pin far enough to engage the bolt face, even when I manually retracted the bolt and pushed it in by hand. I know, seems strange but either it was drilled wrong or milled wrong.

Hello, 98Z

All internals are Anderson Manufacturing.

 Overgassing is possible Definitely not undergassing, always strips the next round from the mag and always locks back (after I modified the rotation range on the catch)

 

Thank you all for the input. Thinking an adjustable gas block, low profile, any recommendations?

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5 hours ago, jtallen83 said:

That is what makes this forum the great place it is, no cut and dry "specs" on the big frame. Boils down to trouble shooting by the experts to decipher what parts are not playing well with the system. There is a wealth of knowledge here from members and in the threads. Give the guys some info like a parts list and measurements on the buffer system and odds are something will stand out right away. 

Welcome from Iowa, via N.C.

Ill pull it apart and measure everything i can, thanks!

Edited by Albroswift

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5 minutes ago, Albroswift said:

Ill pull it apart and measure everything i can, thanks!

Buffer, buffer tube depth, spring and number of coils on spring 

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1 hour ago, Albroswift said:

 Hello, Robo

The bolt catch would not rotate on the pin far enough to engage the bolt face, even when I manually retracted the bolt and pushed it in by hand. I know, seems strange but either it was drilled wrong or milled wrong.

There are about 4 different bolt catches for the .308AR format rifles. Have you tried any other parts?

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1 hour ago, Albroswift said:

The photo is simulated, I thought after I was done shooting a photo would be easier then trying to explain so I staged it, I'll look at the case mouth

 

Thank you all for the input. Thinking an adjustable gas block, low profile, any recommendations?

That explains why it looks like an ejected round.  I never would have noticed that, but that's the type of attention to detail these guys have around here.

 

As for the gas block, rule out some other easy items before you drop money on a part you may not need. 

Edited by DNP

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1 hour ago, Robocop1051 said:

There are about 4 different bolt catches for the .308AR format rifles. Have you tried any other parts?

I purchased as a new factory assembeled gun. Like i said in another post, machining looks good, fit not so. 

. Put a gold trigger, M4-72 Brake, Viper HST scope and mount, aligned the floating handguard. Shoots a good group with old brass, different powders different bullets. Only bad groups came with BL-C2. This is the last issue to work out. 

Thanks

 

 

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3 hours ago, Albroswift said:

Hello, Matt 

It is running back plenty far, it chambers the next round and then jambs the spent round on top of it. 

That's physically unpossible my friend. You're saying that in the firing sequence, the bolt extracts the fired round(evidenced by the case mouth being dented by the locking lugs on your barrel extension), strips another cartridge from the mag, and then chambers the stripped cartridge with the spent cartridge trapped behind it. That's physically impossible.

Based on the pics and the bent cartridge here is what I see happening when this occurs; the bolt fails to travel far enough rearward to properly strip the next cartridge, and begins to travel forward again before the extracted brass can clear the receiver. On the way forward, the bolt frictionally grabs the cartridge in the mag and pushes it into the barrel extension locking lugs where it bends and ceases to move, the bolt continues forward stovepiping the spent brass.

That's my assessment.

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10 minutes ago, Albroswift said:

I purchased as a new factory assembeled gun. Like i said in another post, machining looks good, fit not so. 

. Put a gold trigger, M4-72 Brake, Viper HST scope and mount, aligned the floating handguard. Shoots a good group with old brass, different powders different bullets. Only bad groups came with BL-C2. This is the last issue to work out. 

Thanks

 

 

Sorry. I missed that 1st/original post about it being a complete rifle. That still doesn’t change the fact that the part might be wrong. I own a small rifle manufacturing company , and every once in a while the wrong part falls in the wrong parts bin.  I will cuss and spit for an hour, trying to figure out what is wrong with a rifle, only to break it down and realize that I used a part from a different size format firearm. 

PSA  was notorious for this when they started making 308 rifles. 

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1 hour ago, Robocop1051 said:

Sorry. I missed that 1st/original post about it being a complete rifle. That still doesn’t change the fact that the part might be wrong. I own a small rifle manufacturing company , and every once in a while the wrong part falls in the wrong parts bin.  I will cuss and spit for an hour, trying to figure out what is wrong with a rifle, only to break it down and realize that I used a part from a different size format firearm. 

PSA  was notorious for this when they started making 308 rifles. 

Im thinking Anderson has some of those parts bins..

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10 hours ago, Robocop1051 said:

There are about 4 different bolt catches for the .308AR format rifles. Have you tried any other parts?

I purchased as a new factory assembeled gun. Like i said in another post, machining looks good, fit not so. 

. Put a gold trigger, M4-72 Brake, Viper HST scope and mount, aligned the floating handguard. Shoots a good group with old brass, different powders different bullets. Only bad groups came with BL-C2. This is the last issue to work out. 

Thanks

 

 

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DPMS-LR-based recoil system, and the spring is shiit.  The buffer probably doesn't weigh what it needs to, either.  In complete honesty, shiit-can the recoil system completely, and just pick up real Armalite AR-10 Carbine recoil system.  Start there. It needs to be done anyway. You can use the Armalite AR-10 Carbine receiver extension with the 7 5/8" internal depth, or you can use the VLTOR A5 receiver extension.  Same/same.  Any old AR-15 H3 Carbine buffer will work.  Armalite EA1095 buffer spring - <<<   that's the key to the whole thing, right there, and the most important part.  It's cheap, too.  It won't work by itself, so don't get one and just slap it in.  It needs those other two components.

 

Great radius job on their ejector - seriously.  You'll never have any feeding issues because of that ejector, that's for sure.  Squared-off faces on ejectors can cause issues on next-round when the mag is feeding from it's right side.  That bolt will never have those issues. 

What else...  That receiver extension pic that you have up there - it's not even screwed in far enough.  You probably wouldn't be able to take it in another turn, unless you notched the bottom of it to clear that buffer retainer. That's an assembly problem, as well as a hardware problem, if they're not notching it from the factory.  It's shiit anyway, so just get rid of it and get the Armalite or VLTOR extension.

The more pics you post, the more I'm gonna find.  Get a pic of that gas tube, in the upper, with the BCG removed.  I wanna see where it's at in the receiver, and how much it protrudes into the upper...

 

Edited by 98Z5V

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It sounds like a lot of work, but it’s not. 98 is right. The A5 tube, AR10 spring a H3 buffet should run you $40-$50 and only take about 20 minuets to swap out parts. 

We don’t usually suggest shooting handloads or reloads until AFTER the rifle is well broken in. 

The 308AR really likes to run WET during her break in period. Not just “a little here on the wear spots”. We’re talking about Hurricane Katrina kinda wet. 

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