I'm sorry, another over-pressure post....

[Thorspapa]

I've looked through some of the previous posts about problems similar to mine, so I apologize if I'm rehashing an issue, but this is just different enough (to me anyway) to post it. I apologize in advance if I'm being repetitive.
And I need help.
Earlier this year I ordered, and received a Rock River LAR-BT3 in 6.5 Creedmore. Its intended purpose was to start PRS competition, since my son works with a guy that competes. The rifle is kept stock, except for a Vortex scope, and some weights for proper balancing.
I use only factory loaded ammo, since I don't have the time or patience for reloading. I've used Hornady 140 Match, Berger 144 Match (currently my choice), and Winchester 140 Match. I used Ammo Inc 140 Match for initial scope sighting to 200 yds (cheaper).
We were getting used to the rifle's performance at various distances, had shot about 400 rds through it, when we noticed a primer fell out of a fired case. The next few times it started happening more often, and the ejected cases started looking worse. That's when I started to try different factory loads as described above.
The signs are of EXTREME pressure. First I thought there was a carbon build up ring in the barrel/chamber. After a thorough chemical cleaning (left plugged barrel sit overnight with solvent), manual cleaning and rechecking I tried again: symptoms did not change.
Fast forward to experimenting with adjustable gas block, and more cleaning: nothing changed. Adjusted the gas block from full open to where it failed to extract: no real change. The fired brass was VERY difficult to manually extract with the gas closed off. I put original gas block back (since it worked fine in the beginning).
My last range outing for testing after ANOTHER thorough cleaning only showed me the problem is actually getting worse. Every ejected case is now missing the primer, and the rims are bent. Also noticed that accuracy has fallen off, from sub MOA to over 1.5 MOA. There's some damage from what I assume is the ejection port on the neck of the fired brass.
I should also note that I can easily chamber an unfired round with a gentle finger push, and the unfired case will readily fall out if I tilt the barrel and gently tap the rifle butt on a table.
I've tried reaching out to Rock River, but they're not answering my emails. The time I called and spoke with someone from Tech Support, they basically blew me off, blamed ALL the factory ammo as a "common industry problem", and "probably a dirty chamber/barrel". It really was a very insulting tone and conversation, so I thanked them for their time, and let it go. It seems I'm on my own here with an almost-new, expensive, non-functioning gas gun. If anybody knows who else to contact at Rock River Arms that would listen, that might help.
I'm expecting a set of Forster gauges tomorrow to check headspace. As to why headspace would change in a few hundred rounds, that's another question.
Anybody out there who can possibly help? I'm attaching a couple of pictures. You can also see neck damage on ejected brass, though it did that from the first day, before the over-pressure signs started.
Any answers are fully appreciated.

 

[BuildingConceptsllc]

So you put 400 rounds through it then this started happening? I mean, there's lots of guys here more knowledgeable on AR's than I am, but it sure sounds like it's dirty. How and what are you cleaning it?

 

[Bigjake83]

I've looked through some of the previous posts about problems similar to mine, so I apologize if I'm rehashing an issue, but this is just different enough (to me anyway) to post it. I apologize in advance if I'm being repetitive.
And I need help.
Earlier this year I ordered, and received a Rock River LAR-BT3 in 6.5 Creedmore. Its intended purpose was to start PRS competition, since my son works with a guy that competes. The rifle is kept stock, except for a Vortex scope, and some weights for proper balancing.
I use only factory loaded ammo, since I don't have the time or patience for reloading. I've used Hornady 140 Match, Berger 144 Match (currently my choice), and Winchester 140 Match. I used Ammo Inc 140 Match for initial scope sighting to 200 yds (cheaper).
We were getting used to the rifle's performance at various distances, had shot about 400 rds through it, when we noticed a primer fell out of a fired case. The next few times it started happening more often, and the ejected cases started looking worse. That's when I started to try different factory loads as described above.
The signs are of EXTREME pressure. First I thought there was a carbon build up ring in the barrel/chamber. After a thorough chemical cleaning (left plugged barrel sit overnight with solvent), manual cleaning and rechecking I tried again: symptoms did not change.
Fast forward to experimenting with adjustable gas block, and more cleaning: nothing changed. Adjusted the gas block from full open to where it failed to extract: no real change. The fired brass was VERY difficult to manually extract with the gas closed off. I put original gas block back (since it worked fine in the beginning).
My last range outing for testing after ANOTHER thorough cleaning only showed me the problem is actually getting worse. Every ejected case is now missing the primer, and the rims are bent. Also noticed that accuracy has fallen off, from sub MOA to over 1.5 MOA. There's some damage from what I assume is the ejection port on the neck of the fired brass.
I should also note that I can easily chamber an unfired round with a gentle finger push, and the unfired case will readily fall out if I tilt the barrel and gently tap the rifle butt on a table.
I've tried reaching out to Rock River, but they're not answering my emails. The time I called and spoke with someone from Tech Support, they basically blew me off, blamed ALL the factory ammo as a "common industry problem", and "probably a dirty chamber/barrel". It really was a very insulting tone and conversation, so I thanked them for their time, and let it go. It seems I'm on my own here with an almost-new, expensive, non-functioning gas gun. If anybody knows who else to contact at Rock River Arms that would listen, that might help.
I'm expecting a set of Forster gauges tomorrow to check headspace. As to why headspace would change in a few hundred rounds, that's another question.
Anybody out there who can possibly help? I'm attaching a couple of pictures. You can also see neck damage on ejected brass, though it did that from the first day, before the over-pressure signs started.
Any answers are fully appreciated.

You need to increase your buffer weight, here's a good place to start.

Heavy Buffers | Products | .308 Rifle

 

[Thorspapa]

So you put 400 rounds through it then this started happening? I mean, there's lots of guys here more knowledgeable on AR's than I am, but it sure sounds like it's dirty. How and what are you cleaning it?

I normally clean after each session, so about 100 rds per. I wet the barrel with Hoppe's copper remover, then let sit while I clean the bolt and components. I then run another wet patch before using brass brushes on barrel and chamber. I run wet patches through until all the blue/green copper residue is gone. Next I run a wet patch of regular Hoppe's, let sit a few minutes, do the brass brushes again, and run wet patches until there's no residue coming out on a wet patch. I then dry patch it. Done. Been doing the same thing since my Camp Perry National Matches days in the 80s. Has always worked for me.

 

[Thorspapa]

You need to increase your buffer weight, here's a good place to start.

Heavy Buffers | Products | .308 Rifle

I tried a heavier spring, not a heavier buffer (didn't have one available) with no change in the damage to the fired brass. The only change being that bolt failed to lock back on empty magazine most times. The question in my mind is: everything originally worked, until it didn't. The buffer, the spring, the gas block were all working beautifully, then things started to go south, and in a very short time period?

 

[SupressYourself]

Since you said you have this problem even with gas turned off, I don't think any combination of buffer and spring is going to help.
Do you have access to a bore scope? -- If not, I would get one. They can had pretty cheap on the jungle website.
You may have a "carbon ring", which is an extra thick layer of carbon usually about where the neck of the case ends. Often, "normal" cleaning is not able to address them, and they can substantially increase chamber pressure. There's plenty of threads on getting rid of them, but I would confirm with a bore scope first.

 

[BCP]

I'd make up a dummy round using a sized piece of brass and whatever bullet (140gr etc) to say 2.83. Then black magic marker all over the bullet and case shoulder and feed it from the mag normally (let the bolt slam home). Then extract it. It could be a short chamber and some bullets that are larger/longer get crammed in there creating pressure.

 

[Bevo]

I had similar issues with my 6.5CM gas gun. I went to a heavy buffer like @bigjake83 mentioned and also swapped the bolt to a JP. No more problems.

 

[LRRPF52]

Does it only do this with that Ammo Inc. ammo, or all of them?

 

[bfoosh006]

Does it only do this with that Ammo Inc. ammo, or all of them?

This... the 4 cases photo are those all Ammo Inc. ?
The neck deformity pic can be typical on ejection, the neck is probably contacting the lugs by the ejection port.
FWIW, your chamber looks smooth judging by the brass pics.

What buffer weight comes in your RRA ?... can you link to your specific model ?

 

[Cascade Hemi]

Put me down for short throat or carbon ring in the throat.

You can get a cheap bore scope on Amazon for around $50.

 

[NHPiper]

Have you run a bore scope through to confirm there definitely isn't a carbon ring. This sounds like the symptoms. I ran into this issue on an SP10 at about the same round count and it was the culprit.

Large frame 6.5mm or 6mm get the carbon ring much faster than bolt guns, at least in my experience. Like almost twice as fast.

Also agree that the buffer weight should help. But my factory SP10 didn't need that adjusted at all even to run suppressed.

Carbon rings are a PITA to get out. I learned to clean it more often with C4 and patches and sometimes a few quick passes with a bronze brush.

 

[Thorspapa]

Since you said you have this problem even with gas turned off, I don't think any combination of buffer and spring is going to help.
Do you have access to a bore scope? -- If not, I would get one. They can had pretty cheap on the jungle website.
You may have a "carbon ring", which is an extra thick layer of carbon usually about where the neck of the case ends. Often, "normal" cleaning is not able to address them, and they can substantially increase chamber pressure. There's plenty of threads on getting rid of them, but I would confirm with a bore scope first.

I do not have a bore scope at this time. Something else I'll have to pick up for troubleshooting.

 

[Thorspapa]

Have you run a bore scope through to confirm there definitely isn't a carbon ring. This sounds like the symptoms. I ran into this issue on an SP10 at about the same round count and it was the culprit.

Large frame 6.5mm or 6mm get the carbon ring much faster than bolt guns, at least in my experience. Like almost twice as fast.

Also agree that the buffer weight should help. But my factory SP10 didn't need that adjusted at all even to run suppressed.

Carbon rings are a PITA to get out. I learned to clean it more often with C4 and patches and sometimes a few quick passes with a bronze brush.

I understand, but I don't have access to a bore scope at this time. I have let barrel sit overnight with solvent, then scrubbed barrel and chamber like a madman. Ran wet patches until they came out pristine. I don't know how a carbon ring would be still present, but without a bore scope I can't say for certain.

 

[Thorspapa]

This... the 4 cases photo are those all Ammo Inc. ?
The neck deformity pic can be typical on ejection, the neck is probably contacting the lugs by the ejection port.
FWIW, your chamber looks smooth judging by the brass pics.

What buffer weight comes in your RRA ?... can you link to your specific model ?

The specific model is the Predator HP 65C LAR-BT3 with 24" barrel. I don't know the buffer weight, its not listed in the specs, and I lack a scale to weight precisely. Those 4 cases are a mixture of Berger 144 Hybrid, and Winchester 140 Match. I used the Ammo Inc brass to show rim deformation, because its the softest brass.

 

[Thorspapa]

Does it only do this with that Ammo Inc. ammo, or all of them?

It does it with all the ammo listed above. I used the Ammo Inc brass in the picture showing the primer pocket, because its the softest, and it shows the deformity better.

 

[Thorspapa]

I'd make up a dummy round using a sized piece of brass and whatever bullet (140gr etc) to say 2.83. Then black magic marker all over the bullet and case shoulder and feed it from the mag normally (let the bolt slam home). Then extract it. It could be a short chamber and some bullets that are larger/longer get crammed in there creating pressure.

I did not do it exactly like you describe, but what I have done is installed a shortened firing pin (safety first), loaded several rds from mag, letting the bolt strip them from mag and seat each one. They eject with ease by hand cycling, and there are no scratches or marks on them after ejecting them. I used a jeweler's magnifier/lamp combination that magnifies to 10X: Cant see anything abnormal on the ejected loaded ammo.

 

[Thorspapa]

By the way. I want to thank all who have responded to this post, as I have myself run out of ideas, so suggestions are appreciated. Thank you.

 

[bfoosh006]

Could you post some pics of the buffer, and measure its OAL.

( At one time RRA used a one off 2.25" carbine buffer, with their oddball BCG... and just making sure since RRA webpage is not very discriptive )

It does sound like a heavier buffer would help... but measurements first.

And does someone have a scale that could measure up to 5.6'ish oz'ish ? Kitchen scale ?

This link appears to be using a 3.25" buffer... but no weight listed.
https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=1381

Your RRA buffer might be 2.9oz-3.0oz.... that is IMHO, to light.

You also might benefit from a Adj. GB.... just sayin'

 

[Shoots 700's]

All my issues with 6.5 and 308 gas guns have come when using a carbine style stock/weights. Move to a Magpul PRS stock and rifle buffer and spring and all the issues go away

 

[NHPiper]

The specific model is the Predator HP 65C LAR-BT3 with 24" barrel. I don't know the buffer weight, its not listed in the specs, and I lack a scale to weight precisely. Those 4 cases are a mixture of Berger 144 Hybrid, and Winchester 140 Match. I used the Ammo Inc brass to show rim deformation, because its the softest brass.

What I found is the amount of scrubbing I was normally doing wasn't even remotely close to enough with C4. Once it's backed on it's a pain. The Teslong Amazon borescope is worth the money.

 

[45-90]

I don't have continual brass problems with the AR 10 or 15.
Carbine or rifle stock. I run mostly carbine stocks.
All are handloads... none have ever had a factory load fired in them.

Everything is mil spec or standard springs and buffers except 9mm.
I use a lot of adjustable gas blocks to tune to the load. Many times drill out tve gas port size.
The 338 Ruger Compact Magnum runs max magnum book loads 62kPSI to 65k PSI, with no issues, the lower is off the 308 AR10 carbine, standard everything, with an adjustable gas block,... change to the 6 5 CM same standard lower, no issues.
Same with the 308 and the 6.5 CM semi autos, they receive same 65,000 psi loads according to QL, as the bolt guns...just turn the gas down 7 clicks for light loads on the SA adj gas block.
So, ...Add and adjustable gas block and tune for your factory ammo.
Here's the 338 RCM in 18" AR 10, a necked up 6.5 PRC case to 338...no brass issues.

 

[Thorspapa]

All my issues with 6.5 and 308 gas guns have come when using a carbine style stock/weights. Move to a Magpul PRS stock and rifle buffer and spring and all the issues go away

I actually tend to agree with you on this. My concern in this instance is due to the fact that it functioned beautifully for a few hundred rounds before the over-pressure signs started.

 

[Thorspapa]

I don't have continual brass problems with the AR 10 or 15.
Carbine or rifle stock. I run mostly carbine stocks.
All are handloads... none have ever had a factory load fired in them.

Everything is mil spec or standard springs and buffers except 9mm.
I use a lot of adjustable gas blocks to tune to the load. Many times drill out tve gas port size.
The 338 Ruger Compact Magnum runs max magnum book loads 62kPSI to 65k PSI, with no issues, the lower is off the 308 AR10 carbine, standard everything, with an adjustable gas block,... change to the 6 5 CM same standard lower, no issues.
Same with the 308 and the 6.5 CM semi autos, they receive same 65,000 psi loads according to QL, as the bolt guns...just turn the gas down 7 clicks for light loads on the SA adj gas block.
So, ...Add and adjustable gas block and tune for your factory ammo.
Here's the 338 RCM in 18" AR 10, a necked up 6.5 PRC case to 338...no brass issues.

I DID install an adjustable gas block for testing. Ran from full open to closing it until it failed to extract. The extracted brass still had the damage, and manually extracting it was HARD.

 

[Thorspapa]

I'm going to look for a bore scope. I really need to see what it looks like inside that barrel. What bore scopes would be easy to use (do not require oddball apps installed on PC to connect with WiFi, and that connect directly by cable), that offer a reasonably good view?
My reasoning on this goes like this:
Since opening or closing the gas has had no effect on pressure signs, there's two possible components involved in the problem, the barrel, and the bolt group. I don't have a spare bolt group to swap with at this time, but I could verify the barrel is truly clean and undamaged with a bore scope.
I just rechecked Rock River's website after leaving another message, and they claim that their rifles have a lifetime warranty for defects to the original owners. Assuming I can get this rifle shipped back to them (they would have to issue me a Return Authorization Number first), I'll need to verify the barrel DOES NOT truly have carbon build up in it, or they'll just charge me for repairs. Ergo, I'm going to need a bore scope.

 

[NHPiper]

I'm going to look for a bore scope. I really need to see what it looks like inside that barrel. What bore scopes would be easy to use (do not require oddball apps installed on PC to connect with WiFi, and that connect directly by cable), that offer a reasonably good view?
My reasoning on this goes like this:
Since opening or closing the gas has had no effect on pressure signs, there's two possible components involved in the problem, the barrel, and the bolt group. I don't have a spare bolt group to swap with at this time, but I could verify the barrel is truly clean and undamaged with a bore scope.
I just rechecked Rock River's website after leaving another message, and they claim that their rifles have a lifetime warranty for defects to the original owners. Assuming I can get this rifle shipped back to them (they would have to issue me a Return Authorization Number first), I'll need to verify the barrel DOES NOT truly have carbon build up in it, or they'll just charge me for repairs. Ergo, I'm going to need a bore scope.

This is the one you want. It's great and I use it all the time.

Teslong Rigid Rifle Borescope, 0.2inch Rod Digital Gun Barrel Bore Scope Gun Cleaning Camera-Fits .20 Caliber & Larger Hunting Shooting Firearms, 26inch Long Insertion Tube & 4.5inch 1080P HD Screen https://a.co/d/dWAtY3S

 

[NHPiper]

This is the one you want. It's great and I use it all the time.

Teslong Rigid Rifle Borescope, 0.2inch Rod Digital Gun Barrel Bore Scope Gun Cleaning Camera-Fits .20 Caliber & Larger Hunting Shooting Firearms, 26inch Long Insertion Tube & 4.5inch 1080P HD Screen https://a.co/d/dWAtY3S

People can go nuts with these, but I have found it's helpful for me to make sure that I don't have burns or damage in barrels and that I am staying on top of carbon rings. It's helped how I clean barrels too.

 

[232593]

The specific model is the Predator HP 65C LAR-BT3 with 24" barrel. I don't know the buffer weight, its not listed in the specs, and I lack a scale to weight precisely. Those 4 cases are a mixture of Berger 144 Hybrid, and Winchester 140 Match. I used the Ammo Inc brass to show rim deformation, because its the softest brass.

What is the length of the gas system on that 24” barrel?

 

[LRRPF52]

I’m wondering about early port erosion if it’s 24” RLGS.

My .260 Rem RLGS 22” runs like a raped ape, shoots like a dream, but it has a Bartlein barrel spun-up and chambered/profiled by GAP.

I’ve never run factory ammo through it though. I'm well over 2000 rounds on it.

 

[Thorspapa]

This is the one you want. It's great and I use it all the time.

Teslong Rigid Rifle Borescope, 0.2inch Rod Digital Gun Barrel Bore Scope Gun Cleaning Camera-Fits .20 Caliber & Larger Hunting Shooting Firearms, 26inch Long Insertion Tube & 4.5inch 1080P HD Screen https://a.co/d/dWAtY3S

I'm ordering it today per the link, thank you.

 

[Thorspapa]

What is the length of the gas system on that 24” barrel?

Measured from the gas block to where tube ends inside upper its 15". I believe that's whet they call "Full Length" gas system in their website.

 

[45-90]

Measured from the gas block to where tube ends inside upper its 15". I believe that's whet they call "Full Length" gas system in their website.

Sounds like a rifle length gas tube...but has nothing to do with the problem.
It appears to me, with many factory loads basically failing, with severe over pressure signs....the rifle needs to go back to Rock River, ..like yesterday, ...send a few over pressure cases along with the rifle.
A good bore scope is nice to have, and puts truth of barrel quality and chambering job in the hands of the shooter.
Most expensive barrels are pretty darn good...but need checked.
I've had one barrel that the maker of moderately expensive barrel, tried to lie to me about all barrels passing quality inspection before being shipped...
I sent him the photo of the inside of his fully inspected barrel..."Oh, you have a bore scope!" Was his reply...I ended up sending the barrel back, but he tried to run out the 30 day return policy, until I got a hold of another guy who took over the account, and actually gave me good customer service, and replaced the barrel, with only a few days to spare, on the return policy.

 

[MarshallDodge]

Lately I have been seeing posts from guys who like Free All penetrant for removing carbon from their barrels. They sell it at my local hardware store.

You could try wetting a patch with Free All and letting it soak in the throat for a few days, then follow up with a bronze brush.

 

[Thorspapa]

I ordered the Teslong scope TSNTG 100 with the flexible probe. I looked at the chamber shoulder, and where the cartridge neck ends. It looks CLEAN. So I scoped 2 other rifles I have in 308 for comparison since now I have a scope, and I'm ashamed to admit that now I know what a carbon ring looks like, since both of those rifles had them. Not bad, but they were there. I need to properly clean them now.
Armed with that information, I re-contacted Rock River Customer Service. I was able to get somebody on the phone, and they finally provided a Return Label and Return Authorization Number. Shipped it back to them earlier today. And now I wait.
Thank you everyone for your input.
And the bore scope IS an important tool to have for troubleshooting. I'm glad to have one now. A week ago, I wouldn't have considered getting one, now I'd recommend anyone having trouble to get one.

 

[SolidCopper]

Did you get your rifle figured out?

 

[mtrmn]

Did you get your rifle figured out?

I second this. I missed this thread until now. Looking at the brass failures through the WEB of the case, through the thickest/strongest part of the brass, brings back memories of my experience with LC 308 brass. I culled all the brass and have not had another problem. I realize this guy is dealing with factory ammo, and it is showing other pressure-type signs as well, but a failure through the web tells me the brass is faulty.

 

[Thorspapa]

Sorry that I've neglected the follow up, but the problem was resolved. Rock River finally answered my written inquiries, and since their rifles are supposed to be guaranteed against defects for lifetime of owner, they sent me a prepaid shipping label to send it back. Two weeks later I received a phone call from them, explaining that the chamber in the barrel had been cut too short, and they had run a reamer through it to match it to the proper specs. They apologized for the troubles it had caused, and two days later I received the rifle back.
I was relieved they had found something (and also suspicious that it'd been actually fixed), so first I used my bore scope: it definitely looked like some machining had been done in the area where the bullet leaves the neck of the case (where the "jump" occurs), which would make sense, since there needs to be some space there or too much pressure will build up. Too much space before the bullet touches the barrel lands can also lead to a decrease in accuracy, therefore my apprehension.
I again tested with several factory offerings: Hornady 140 ELD Match, Berger 140 Match, and Winchester 140 Match, and was still able to stay under 1/2 MOA at 200 yds. Tested out to 500 yds next, and groups have stayed tight, so accuracy has not suffered.
But the important issue has been resolved: no primer swipes, deformed brass, fallen or flattened primers.
Previously the brass had been ejecting in the 3 to 4 o'clock direction, which I took to mean gas was about correct. But I experimented with adding weight to the buffer. I went from a 5.6 oz buffer weight, to a 7.2 oz weight, and it still locks on empty, but I can stay on target better to see my hits, so it has helped.
So it was an improperly cut barrel after all. Why did it not show the problem until after a few hundred rounds? I did not get an answer to that, but I'm happy the problem is resolved (hopefully), and I might have learned a few things in the process. Thanks to all of you that offered help and insights, its very much appreciated.