A strange problem with 6,5x284 - Pressure

[30BR]

What is red ethanol? You're not using gasohol are you?
All I could find online is that it is denatured alcohol; meaning stuff has been added to it.
I would stop using it, and if you can't get 99% isoproply alcohol, try 0000 steel wool on the loaded cases...

 

[Bob Wright]

Thanks for adding the sideviews. It was my son in law's 243 Win that had a carbon build up at the end of the neck. Of course, it would pinch that cartridge down with disastrous results, blew the primers and destroyed the cases, 2 in a row. The only soot on those cartridges was at the the outside chamfer of the case indicating that "pinch".
Secondly, you have a obvious ring around the body shoulder junction as if excessive forming might be taking place, indicating headspace needs to be verified from unfired new, to fired cases.
At least look at headspace and for carbon build up running the suppressor.
You were asking why a suppressor causes excess carbon build up. Hot particles will attach to the colder material containing it, which is your chamber/bore. A suppressor gives the dirty hot gas more time to attach a greater amount of these hot particles. As far as why on some guns it doesn't foul up must be a component (powder, primer, neck tension) or a specific cartridge design issue that is an anomaly, like this.
I have no suppressors to lend you that experience.

 

[Bob Wright]

There is something on the cases, not shure what it is.?

I've left case lube on prepped brass and it looks like that. I clean them better before storage now.

 

[Toydy]

Are we sure it's not fouling? If it takes 10 shots before it shows pressure it seems like a build up after repeated shots?
How much copper comes out when you clean?

 

[ladebenken]

Very little copper fouling.

 

[Frog4aday]

There was a thread on here a few months ago about a gentleman who was trying to remove a carbon ring from his rifle. Pressure issues, just as you describe. He had a bore scope so was able to see it. The post was about all the things he tried to get rid of it. Bore scrubbing with various solvents, to include many specifically designed to remove carbon, had no effect. In the end, the only thing that got rid of it was JB Bore Paste and elbow grease, over and over, until it was scoured out. I suspect you are in the same boat. You clean and just enough carbon gets removed that all seems fine...at first. Then enough builds back up on top of the really hard, baked on 'ring' that is already there - after just a few shots - and your pressure problems return.

When you add in "using a suppressor", that ups the odds this is the problem.

The "other" factor was the powder being used. And I don't know what you are using and it doesn't really matter at this point. But in his case, he had switched to a new powder and it was fouling his gun much faster than his previous powder, which is how the carbon ring got a 'head start' on him and became such a bear to remove. His previous powder and cleaning routine were fine. With the 'new' powder, the carbon buildup was happening much quicker and it got 'baked in' and nothing removed it until he got an abrasive paste and scrubbed, scrubbed, scrubbed. Said it was great therapy for his recently operated on shoulder, ha!

I know you are frustrated. I feel for you. But I'm betting you have a nice, hard, baked in carbon ring going. And it is going to take a lot of work to remove it, which isn't what you want to hear. But it sure beats throwing the whole works into the ocean...right? Good luck.

 

[300 whby]

I have the same issue with my 7stw. It's nothing special, it's a 700 action trued up and an international 28" heavy barrel on a mdt ess chassis with a trigger tech diamond trigger.
I built it over the winter and the chamber was specifically made for the long Berger 195 eol bullet. I received my load data direct from Berger. I have 2 unusual findings with this gun.
1) like you my loads are running at the very low end of the recommended range and with 7828 it is actually below the lowest recommended load. A half grain more blows cases, leaves ejector marks, and makes the bolt nearly impossible to open. Further, at a half grain more it smashed the injector pin so hard that the spring was done and the pin was actually bent. However, with this light load my velocity is about 60 m/sec faster than top speeds expected by the hottest loads recorded in the available data.
2) As for the temperature insensitivity boasted by powder manufactures....BS!!!!
In this rifle regardless of powder tried (7977, 7828, H1000, and Retumbo) all of them require seriously reduced summer loads to avoid blowing cases. For example, with 7977 my winter load (still not max by the books, but max for my rifle) is 76g. This is anywhere from -30 to -50 celcius where I live in northern saskatchewan. My summer load with this powder is 71.5g but I have light pressure signs (slightly heavier bolt lift, ejector marks, and brass fails faster). This is in our current +20 celcius weather.
However, it's accurate so I shoot it that way.
I have sent the rifle out to 3 highly recommended smiths who have all returned the rifle saying that there is nothing unusual/wrong with it.
So, I have come to the conclusion that in the same same vein that we know know 2 rifles will not like the same bullet, some rifles may just be wildly atypical. Further, I've learned my lesson in terms of advertising as those temperature insensitive powders are anything but insensitive.
It is interesting to see the possible issues/causes posted in response to your post. Most seem very reasonable and logical. I tried it all to no avail.

I have the same with a semi custom 7mm rem mag with match grade barrel, my gun runs the same velocities in the reloading manual with 4-6 grains below listed starting loads.. but it shoots great so I've stopped chasing the tail of the dragon & just use it as it is......

 

[Bob Wright]

Find access to a borescope. Check with a gunsmith in your locale. These are readily available to purchase as well. Lyman makes a good one.

 

[SteveBurton]

I've read all of the comments but I don't see one thing. Have you tried shooting without the suppressor attached to see what happens? If the pressure signs return, you can eliminate that as a problem. If they don't, you may have to consider shooting without it.

 

[ladebenken]

Well now i have got some new expirience.

I used to clean this rifle like all my others, including my comp rifles in 6,5 swede, which i shoot 4-5000 shots with a year.

Well it seems it hasn`t been good enough. It has now gotten what i call a judgementdaycleaning. About 5 days soaked with different chemicals, brushed like f... each day and polished 4 times with gold medallion.

Today i shot 35 shots with no problems. Same brass, same load, same bullet, with silencer.

5x5 shots at 430 meters - 480 yards.

Todays best group, and the worst.. Looks like that Krieger barrel is ready for hunting

 

[30BR]

Congratulations on figuring it out! I was hoping we would hear your results!

 

[Bob Wright]

Ditto 30BR comment. This does happen to many rifles. Still going to get that borescope for my rifles. Curiosity....

 

[ladebenken]

Yes i am also going to buy a borescope. I think its good learning to use a borescope while shooting and cleaning.

 

[Bob Wright]

Yes i am also going to buy a borescope. I think its good learning to use a borescope while shooting and cleaning.

Do you live outside the USA? Hoping you can get one easily.