Yep, another broken-extractor thread

[SDW]

Hi all. While out in the desert shooting the other day, my rifle's extractor broke. I'm sure there's various reasons for it and I know it is not uncommon. First off, relevant info:

• Rifle has a 20" DMR profile barrel, made by Ballistic Advantage, rifle-length gas and rifle recoil system
  
• Bolt is also Ballistic Advantage, purchased with the barrel
  
• Total round count on the bolt/barrel is somewhere under 300
  
• Extractor broke while I was firing some work-up loads of 123 ELD bullets on 8208 XBR (broke at 3rd round of 27.9gr)
  
• No, there is no rubber donut around the extractor spring (spring is one of the longer "enhanced" types from BCM)
  
• Yes, I will be purchasing a SixFiveArms bolt as a replacement as soon as they're back in stock, hopefully this week
  

I'd like to buy a good quality (superior to BA's) replacement extractor, so as to put my BA bolt back in service, at least as a spare. Is this one of a decent type. Says it's made of MIL-S-5000 Steel, same stuff that SixFiveArms extractors are made from, so I assume it's 'the good stuff':

https://www.blackriflearms.com/-65-Grend...p_297.html


I know that JP also makes and "enhanced" extractor, but those cost nearly what a whole bolt costs from SFA/BFT. So I'm not leaning in that direction.

BTW, I was doing a little reading on this subject, various sites. Found a comment in this reddit thread discussing a broken Grendel bolt, in this case it was an Aero precision bolt/extractor. Aero has owned Ballistic Advantage for a few years now, so perhaps the parts come out of the same bin:

https://www.reddit.com/r/guns/comments/c...s/ewmw5ji/

No need to read the whole thing. Per one responder there, the gist is that:

"Aero Grendels use C158 bolts/extractors and are one of the very few in the industry that still do. No bueno for Grendel."

I wonder if this is true. If so, then the break shouldn't be so surprising.

EDIT: BA says their Grendel extractors are (were) made from 4340 steel, which is the same as MIL-S-5000 steel, apparently:

https://www.ballisticadvantage.com/6-5-g...tride.html

So maybe never mind that.

[Lastrites]

I have at least 500 factory rounds on a black rifle arms bolt, so far so good, but I still had bought several replacement extractors just because. Need another bolt for inventory as well as the next thing may be a lug.

[SDW]

Thanks for the info on Black Rifle Arms, and the tip on buying at least two extractors. Good idea. Regarding the spare bolt, see that last bullet point in my list.

[SDW]

Well that's a pisser. Something's broken with Black Rifle Arms' web site. Can't add anything to a cart. It throws an error. I will have to look elsewhere. Or I could just "pick up a telephone" as we used to say, and give them the order.

[StoneHendge]

I've been through 2 Black Rifle Arms Type 1 extractors in my 243 LBC. Each lasted a little over 500 rounds. Barrel is an 18" MLGS so it suffers from timing issues and the extractor is subjected to excess stress. Nonetheless, I wouldn't view their extractors as upgrades.

My old 22" JP 6.5G with RLGS couldn't get close to 28 grains of XBR with 123s. Pressure may be why your extractor broke.

[SDW]

Nonetheless, I wouldn't view their extractors as upgrades.

My old 22" JP 6.5G with RLGS couldn't get close to 28 grains of XBR with 123s. Pressure may be why your extractor broke.

Right. I came to that conclusion about the BRA extractor after reading Ballistic Advantage's specs. They are made of the same steel anyway. At $20/each I'll settle for no worse I suppose. I'll buy two of them. And as already said, pick up one of BFT's bolts ASAP.

I agree with you on the XBR load. Shots began behaving strange above a certain loading. Somewhere around 27.6 gr the bolt started to lock back partially. And brass path changed from the normal 4 o'clock direction to more of a 2-3 o'clock direction. And the groups began opening way up.

So, looking at my targets and fired brass this morning, I came to the conclusion that with XBR I would not go beyond 27.3 gr again. That group was a respectable .8", even if average velocity was only around 2390 FPS.

Of the four powders I was testing, I think I was most impressed by TAC. AA2520 didn't do so bad either.

[lazyengineer]

I've snapped a PSA extractor and BRA extractors. Never broke the extractor on my sixfivearms TEAM bolt though. If I didn't already have 3 spare extractors and a spare complete PSA BCG, I'd probably buy another sixfivearms bolt.

[Klem]

Guys,

With the 123ELD and 8208 XBR I would not load above 26.2gn at 2.260" OAL.

XBR reaches the SAAMI pressure limit at 26.2gn and at that point is 99% full. Anything above 26.5 and it starts to compress. The 8208 pressure curve gets steep quickly when compressed, and when it gets to compressed it is already over pressure. That's why it is so unforgiving. Your gun is being hammered to death and the weakest link is the extractor.

Find a stronger extractor and it will be bolt lugs next.

[A5BLASTER]

Right. I came to that conclusion about the BRA extractor after reading Ballistic Advantage's specs. They are made of the same steel anyway. At $20/each I'll settle for no worse I suppose. I'll buy two of them. And as already said, pick up one of BFT's bolts ASAP.

I agree with you on the XBR load. Shots began behaving strange above a certain loading. Somewhere around 27.6 gr the bolt started to lock back partially. And brass path changed from the normal 4 o'clock direction to more of a 2-3 o'clock direction. And the groups began opening way up.

So, looking at my targets and fired brass this morning, I came to the conclusion that with XBR I would not go beyond 27.3 gr again. That group was a respectable .8", even if average velocity was only around 2390 FPS.

Of the four powders I was testing, I think I was most impressed by TAC. AA2520 didn't do so bad either.

That timing difference of where your brass is landing is telling you what the problem is and why you broke the extractor.

It's over gassing and trying to extract the case while its pressured to high to do so.

Call AA and see if they have an extractor or 2 instock. If they do, buy them, install and do something about the overgassing issue of your load and buffer setup.

Anything past 3 o'clock is overgassed.

[biodsl]

Call AA and see if they have an extractor or 2 instock. If they do, buy them, install and do something about the overgassing issue of your load and buffer setup.

Short of installing an adjustable gas block, is adding a heavier buffer the solution?

[tdbru]

biodsl,
here's what i tried out and decided to keep. i have a rifle length buffer tube, rifle length buffer spring. rifle length gas system. fixed gas block, however. but i wanted to slow the cycle rate way down for a couple of reasons.

as a kid growing up all i heard about the M16 was that the gas system dumped gas right into the action and it got dirty fast and would fail to function then. i'd never had an AR before so i never got a good look at how the gas system was designed and worked. last year i finally got one.

upon taking it apart and investigating, the expansion chamber in the BCG dumps excess gas out the ejection port through the bolt vents. that shouldn't "dirty up" the action. but what seemed to me a possibility was that if the BCG moved back far enough to expose the end of the gas tube while there was still some, or a lot, of pressure in the barrel, a lot of the powder gasses would indeed be dumped into the action.

since i am not concerned about a fast cycle rate, since i only slow fire the rifle anyway, whether plinking or hunting, it seemed to me that the RLGS would delay the BCG movement vs mid or short length gas system, that a GI BCG would weigh more than these ones that have been lightened for "competition", which i assume was to get a higher cycle rate. also i added a heavibuffer (11oz if i recall correctly) instead of the GI buffer. this adds mass to the reciprocating system and should slow the movement of the BCG. i thought if the BCG gas key never came back past the end of the gas tube until the pressure in the barrel was a lot lower than "normal" then a lot less powder fouling (hopefully none) would get dumped into the action from the end of the gas tube.

this seems to be the case. the action doesn't get very dirty when shot. as a bonus i think delaying the movement of the BCG so that the bolt doesn't start to rotate and extract until the pressure in the bore is even lower than "normal" seems to have an added benefit on lowering the stress on the extractor. i'm running without the rubber donut around the extractor spring. no problems with either extraction or ejection. action does indeed run "slower" but still runs faster than i can get aimed on a target so it's a don't care to me in that regard.

i think there's a lot less stress on the extractor as it rotates on the pivot pin while chambering a round without the donut. and the action runs enough slower that it doesn't seem to need the donut either. so far i've not had any issue with the BCG not coming back far enough to function correctly, whether that is locking the bolt back after the last round or any kind of feeding issue.

another result of the heavibuffer is that the rifle balances a bit further to the rear as compared with the GI rifle buffer installed. not a big deal but it's slightly noticeable. i suspect an adjustable gas block could be used to accomplish the same thing.

i think the more you can delay the movement of the BCG after the round is fired, the lower the stress on the extractor, and the cleaner the action will run. of course you do need enough gas to cycle the action. with just a normal gas block on my rifle, the gas chamber in the BCG is getting fully pressurized as normal, i think, but with the extra mass in the reciprocating assembly, the pressure in the gas tube is much lower by the time the BCG gas key clears the end of the gas tube and the pressure in the bore at the bolt rotation/extraction is a lot lower than "normal" as well. which i think leads to less stress on the extractor and seems to lessen the amount of powder fouling being dumped into the action. my hypothesis anyway.

in use the action doesn't seem to get very "dirty" from powder fouling. some may find the slower cycle rate rather annoying, particularly the competitive shooter kind of folks. but for slower firing, such as plinking or hunting, you won't be bothered by a slightly slower cycle rate, i wouldn't think. it still cycles much faster than i can get the next precisely aimed shot off so i'm not bothered with the slower cycle time.

just commenting in response to your question. i wonder if the folks who do have an adjustable gas block and have it turned down to where the rifle will just function notice a cleaner action and a lower extractor failure rate?

-tdbru

[LR1955]

Hi all. While out in the desert shooting the other day, my rifle's extractor broke. I'm sure there's various reasons for it and I know it is not uncommon. First off, relevant info:

• Rifle has a 20" DMR profile barrel, made by Ballistic Advantage, rifle-length gas and rifle recoil system
  
• Bolt is also Ballistic Advantage, purchased with the barrel
  
• Total round count on the bolt/barrel is somewhere under 300
  
• Extractor broke while I was firing some work-up loads of 123 ELD bullets on 8208 XBR (broke at 3rd round of 27.9gr)
  
• No, there is no rubber donut around the extractor spring (spring is one of the longer "enhanced" types from BCM)
  
• Yes, I will be purchasing a SixFiveArms bolt as a replacement as soon as they're back in stock, hopefully this week
  

I'd like to buy a good quality (superior to BA's) replacement extractor, so as to put my BA bolt back in service, at least as a spare. Is this one of a decent type. Says it's made of MIL-S-5000 Steel, same stuff that SixFiveArms extractors are made from, so I assume it's 'the good stuff':

https://www.blackriflearms.com/-65-Grend...p_297.html


I know that JP also makes and "enhanced" extractor, but those cost nearly what a whole bolt costs from SFA/BFT. So I'm not leaning in that direction.

BTW, I was doing a little reading on this subject, various sites. Found a comment in this reddit thread discussing a broken Grendel bolt, in this case it was an Aero precision bolt/extractor. Aero has owned Ballistic Advantage for a few years now, so perhaps the parts come out of the same bin:

https://www.reddit.com/r/guns/comments/c...s/ewmw5ji/

No need to read the whole thing. Per one responder there, the gist is that:



I wonder if this is true. If so, then the break shouldn't be so surprising.

EDIT: BA says their Grendel extractors are (were) made from 4340 steel, which is the same as MIL-S-5000 steel, apparently:

https://www.ballisticadvantage.com/6-5-g...tride.html

So maybe never mind that.

Almost 28 grains of XBR with a 123? Surprised you didn't shear bolt lugs too. That load is too hot.

LR55

[A5BLASTER]

Short of installing an adjustable gas block, is adding a heavier buffer the solution?

Yes heavier buffer by useing tungsten weights and can go with a heavier bcg if need be.

His load does sound a bit hot. And I'm sure that isn't helping his parts lifespan. But he could adjust the buffer weight and slow the unlocking down and get the rifle better gassed.

If I'm not mistaken this isn't the first extractor he has broke.

[SDW]

Guys,

With the 123ELD and 8208 XBR I would not load above 26.2gn at 2.260" OAL.

XBR reaches the SAAMI pressure limit at 26.2gn and at that point is 99% full. Anything above 26.5 and it starts to compress. The 8208 pressure curve gets steep quickly when compressed, and when it gets to compressed it is already over pressure. That's why it is so unforgiving. Your gun is being hammered to death and the weakest link is the extractor.

Find a stronger extractor and it will be bolt lugs next.

First off, I'm not here to argue, just to discuss. I'm curious about your data. Hogden's data for XBR and 123gr bullets lists a max of 28.5gr (compressed). I kinda had that in mind as I was figuring my workups. I was half a grain shy of that. They don't say if their data is for bolt gun or AR, I'll admit, but it is repeated in may places, including the "6.5 Grendel Reloading Handbook". And as I was seating bullets I was feeling for compression. I'm sure the bullets did displace some powder up and around, but there was no feel or sound of 'crunch'. Further, this site is full of anecdotal info on people going up to and a slightly beyond 28 gr of XBR under 123gr bullets of various makes. Is there something unusual about the ELDs that require more conservative loadings?

And I'm not saying I think your info is wrong Clem. I guess I'm saying that based on most available data I've seen, I think I had a foundation to at least try the powder weights I did.

In any case, I've already observed that this powder is not the best choice for this rifle. I was getting better results from TAC and AA2520.

That timing difference of where your brass is landing is telling you what the problem is and why you broke the extractor.

It's over gassing and trying to extract the case while its pressured to high to do so.

Call AA and see if they have an extractor or 2 instock. If they do, buy them, install and do something about the overgassing issue of your load and buffer setup.

Anything past 3 o'clock is overgassed.

Makes sense. And it's what I suspected. I didn't mention it before, but that is when my groups really opened up and SD widened noticeably.

I'm surprised my rifle would be overgassed, being that it's rifle with a RLG system (~0.092" port) and a standard rifle buffer, 5 oz? But given enough pressure, anything will become overgassed.

BTW, I wrote to BRA and told them about the issue with their web site. They fixed it quickly and so I ordered two of their extractors.

Yes heavier buffer by useing tungsten weights and can go with a heavier bcg if need be.

His load does sound a bit hot. And I'm sure that isn't helping his parts lifespan. But he could adjust the buffer weight and slow the unlocking down and get the rifle better gassed.

If I'm not mistaken this isn't the first extractor he has broke.

You are mistaken, but that's alright.

Just to emphasize, I never said I was interested in building my rifle to handle ultra hot loads. I'm not sure how you guys came to that assumption. This issue came up while doing work-up testing, which often for various reasons to leads to dead ends.

I just came here to ask about finding a replacement extractor.

[Klem]

First off, I'm not here to argue, just to discuss. I'm curious about your data. Hogden's data for XBR and 123gr bullets lists a max of 28.5gr (compressed). I kinda had that in mind as I was figuring my workups. I was half a grain shy of that. They don't say if their data is for bolt gun or AR, I'll admit, but it is repeated in may places, including the "6.5 Grendel Reloading Handbook". And as I was seating bullets I was feeling for compression. I'm sure the bullets did displace some powder up and around, but there was no feel or sound of 'crunch'. Further, this site is full of anecdotal info on people going up to and a slightly beyond 28 gr of XBR under 123gr bullets of various makes. Is there something unusual about the ELDs that require more conservative loadings?

And I'm not saying I think your info is wrong Clem. I guess I'm saying that based on most available data I've seen, I think I had a foundation to at least try the powder weights I did.

In any case, I've already observed that this powder is not the best choice for this rifle. I was getting better results from TAC and AA2520.

SDW,

I don't think anyone is arguing. That data comes from Quickload. I do not know your case capacity in water so used the default. You may have slightly more or less volume in your cases and this affects pressure slightly.

I use a combination of Quickload, manufacturer tables and this forum to get an idea of where SAAMI max is. I tend to believe QL, I find the loads discussed here are on the hot side. Given the calibre is slow to start with and everyone seems to want to load on the raggedy edge enjoying a few extra fps before something breaks. AR's would have to be the most fragile guns I know so raggedy edge and AR's are a combination asking for trouble. I don't have an issue with keeping spare parts close and treating them like consumables. So, if a part breaks after 500rds the replacement is just the cost of running the gun hot. It's all fairly safe with the weakest link being bolt lugs. Unlikely the thing is going to blow up and frag you.

As for 8208, I find it is a great powder for bullet weights up to 120gn. For 120 and above I prefer the slightly slower H4895.

You won't feel crunching until it is at least 103+% full. By then it is already compressed.

[Lastrites]

Thanks for the info on Black Rifle Arms, and the tip on buying at least two extractors. Good idea. Regarding the spare bolt, see that last bullet point in my list.

Lol, the extra bolt comment was meant towards me, I need another!

[Zeneffect]

My run through quickload and my personal experience tracking on the chronograph mirrors what Klem is saying about xbr 100%.

26.3 is the limit of which I push the 123gr eldm with xbr.

[A5BLASTER]

First off, I'm not here to argue, just to discuss. I'm curious about your data. Hogden's data for XBR and 123gr bullets lists a max of 28.5gr (compressed). I kinda had that in mind as I was figuring my workups. I was half a grain shy of that. They don't say if their data is for bolt gun or AR, I'll admit, but it is repeated in may places, including the "6.5 Grendel Reloading Handbook". And as I was seating bullets I was feeling for compression. I'm sure the bullets did displace some powder up and around, but there was no feel or sound of 'crunch'. Further, this site is full of anecdotal info on people going up to and a slightly beyond 28 gr of XBR under 123gr bullets of various makes. Is there something unusual about the ELDs that require more conservative loadings?

And I'm not saying I think your info is wrong Clem. I guess I'm saying that based on most available data I've seen, I think I had a foundation to at least try the powder weights I did.

In any case, I've already observed that this powder is not the best choice for this rifle. I was getting better results from TAC and AA2520.


Makes sense. And it's what I suspected. I didn't mention it before, but that is when my groups really opened up and SD widened noticeably.

I'm surprised my rifle would be overgassed, being that it's rifle with a RLG system (~0.092" port) and a standard rifle buffer, 5 oz? But given enough pressure, anything will become overgassed.

BTW, I wrote to BRA and told them about the issue with their web site. They fixed it quickly and so I ordered two of their extractors.


You are mistaken, but that's alright.

Just to emphasize, I never said I was interested in building my rifle to handle ultra hot loads. I'm not sure how you guys came to that assumption. This issue came up while doing work-up testing, which often for various reasons to leads to dead ends.

I just came here to ask about finding a replacement extractor.

My apologies I thought you was the same member here not long back that had broke several extractors.

As to your load, I dont really care how hot you run it. It's your rifle and your health do as you choose.

I'm just giving you the best advice I can to fix the issue that caused your extractor to break. Just because you have standard equipment installed doesnt mean the rifle cant be or go overgassed.

Even with all OEM equipment setup rifle length in 556 can be overgassed. As it was designed to be overgassed too keep running under combat situations.

3:30 and later on the clock is undergassed. Anything earlier then 3 is over gassed and getting worse.

[SDW]

SDW,

I don't think anyone is arguing. That data comes from Quickload. I do not know your case capacity in water so used the default. You may have slightly more or less volume in your cases and this affects pressure slightly.

I use a combination of Quickload, manufacturer tables and this forum to get an idea of where SAAMI max is. I tend to believe QL, I find the loads discussed here are on the hot side. Given the calibre is slow to start with and everyone seems to want to load on the raggedy edge enjoying a few extra fps before something breaks. AR's would have to be the most fragile guns I know so raggedy edge and AR's are a combination asking for trouble. I don't have an issue with keeping spare parts close and treating them like consumables. So, if a part breaks after 500rds the replacement is just the cost of running the gun hot. It's all fairly safe with the weakest link being bolt lugs. Unlikely the thing is going to blow up and frag you.

As for 8208, I find it is a great powder for bullet weights up to 120gn. For 120 and above I prefer the slightly slower H4895.

You won't feel crunching until it is at least 103+% full. By then it is already compressed.

Thanks. I just wanted to let you know up front that I wasn't "challenging" your info as I was about to throw out some different numbers I'd dug up. I think we're on the same page. I don't have quickload I'm afraid. And yes, I like that the extractor, and next the lugs, are the "fuse" of the system. Kind of like a truck's u-joints being the most desirable breaking points (though not on the freeway!) in the driveline. Much easier to replace than an axle shaft or ring & Pinion gear.

Darn it, I'd meant to mention but kept forgetting, my brass is once-fired Hornady. Resized with my Lee FL dies. I understand they have greater volume than say, Starline. But I have not cc'd them.

Regarding the crunch, it occurred to me a while back that a good way to load a cartridge like this with it's long bullets would be to get the bullet seating started in the normal way and then invert the press so that the bullet is being push up into the case. Gravity would bring the powder down and around the bullet filling the shoulder area. There'd be much less, and maybe zero crushing of powder grains. I double I'm the first guy to think of this.

Lol, the extra bolt comment was meant towards me, I need another!

Oh sorry! You write like I do sometimes. I tend to leave off the I/you when I'm writing quickly. Anyway, SixFive's bolts should be back in stock very soon.

[SDW]

My apologies I thought you was the same member here not long back that had broke several extractors.

As to your load, I dont really care how hot you run it. It's your rifle and your health do as you choose.

I'm just giving you the best advice I can to fix the issue that caused your extractor to break. Just because you have standard equipment installed doesnt mean the rifle cant be or go overgassed.

Even with all OEM equipment setup rifle length in 556 can be overgassed. As it was designed to be overgassed too keep running under combat situations.

3:30 and later on the clock is undergassed. Anything earlier then 3 is over gassed and getting worse.

Thank you for the info!

I'm sure you're right about it being overgassed by design. Kind of funny though, w/o the 'modern' deflector the brass seems to go any which way. At least it does with my old M16a1 upper. So I don't know if we could use the 'O'clock' method as reliably I don't think, anyway. I never experimented with light an heavy loads in that upper to see what the brass would do consistently. And it's getting off topic.