What is the verdict on this barrel?

[Tidesloe]

Bartlein on the Stw, Brux on the 300 Norma. I'm really starting to believe Im either going to have to go to a faster burning powder like retumbo or h1000 in the Norma or go to a 28" with n570 in the Norma to get a cleaner burn. I may be way off base on those thoughts. I'm not sure, but for now, I'm just keeping a close eye on it and using the c4.

So many variables. I guess thats all you can do is keep an eye on it, and see what its doing. Maybe I get a guicker burn, but what do you mean on a longer barrel? Would that increase the combustion time, giving a more complete burn?
I sure wish I knew what I know now, which is still not much when that STW was brand new. I never imagined I could have that much problem in only 3-400 rounds. One reason I havent worried about it that much.
I didnt develop the load, but it shot well, and I stuck with it.

 

[couesaddict]

If it still looks like you have a carbon ring after all you've done to it, I've had excellent luck with letting a soaked patch sit in the throat for an hour or two with a penetrating oil such as pb blaster then rotating a brush slowly with a drill in there also soaked with the penetrating oil. Pretty effortless way of getting rid of it for me. Also, I think I'd do some work on the firecracked throat and lands with jb's to try and smooth it out once it's good and clean. Will more than likely lose your ejector marks after all of these things are accounted for. I really think with all of us recently getting borescopes, we're just seeing what was always there in our trusty rifles. I'm not ready to panic yet...

 

[Tidesloe]

If it still looks like you have a carbon ring after all you've done to it, I've had excellent luck with letting a soaked patch sit in the throat for an hour or two with a penetrating oil such as pb blaster then rotating a brush slowly with a drill in there also soaked with the penetrating oil. Pretty effortless way of getting rid of it for me. Also, I think I'd do some work on the firecracked throat and lands with jb's to try and smooth it out once it's good and clean. Will more than likely lose your ejector marks after all of these things are accounted for. I really think with all of us recently getting borescopes, we're just seeing what was always there in our trusty rifles. I'm not ready to panic yet...

Thats true. Lyman made them too cheap. Id never thought of getting a borescope @ $1500., suddenly I saw you can have one for $250., and the thing seems to work pretty well.
Thats a good point. What we didnt know didnt seem to really be hurting us.

 

[MNbogboy]

Have you shot it since your cleaning?
It looks like you got most of any carbon in the neck area as the reamer marks are mostly visable. Carbon in this area impinges on the neck not allowing complete bullet release and hence increased pressure. An old trick was to insert a bullet in a fired case. If it slips right in then the carbon ring in the neck was not the offender.
A carbon ring in the throat itself often can be seen as it leaves marks (scratches) on a bullet when fully inserted into the throat.
These bore cams truly are a godsend when examining before/during/and after cleaning.

On another note, is the ammunition showing the ejector marks different in any way than when it didn't have pressure indicators?
Any change in brass, powder, bullets or any other components could show an increase in pressure.
Also was the ammunition "older" when these indicators showed? Possibility of "cold weld" could also boost up the pressure.

Hope you nail it down.

 

[johnnyk]

I used a Kroil soaked patch and then JB's non-embedding bore cleaning compound to get rid of carbon rings in a 7RM. Same amount of rounds and my barrel looked very similar to OP's.

 

[Tidesloe]

Have you shot it since your cleaning?
It looks like you got most of any carbon in the neck area as the reamer marks are mostly visable. Carbon in this area impinges on the neck not allowing complete bullet release and hence increased pressure. An old trick was to insert a bullet in a fired case. If it slips right in then the carbon ring in the neck was not the offender.
A carbon ring in the throat itself often can be seen as it leaves marks (scratches) on a bullet when fully inserted into the throat.
These bore cams truly are a godsend when examining before/during/and after cleaning.

On another note, is the ammunition showing the ejector marks different in any way than when it didn't have pressure indicators?
Any change in brass, powder, bullets or any other components could show an increase in pressure.
Also was the ammunition "older" when these indicators showed? Possibility of "cold weld" could also boost up the pressure.

Hope you nail it down.

I havent shot it since, and it'll be a week or 2 before I do. The ammo is the same I loaded 2-3 yrs ago. I dont shoot it very often, but getting back to it, and a couple of other rifles. What is " cold weld"?
I located the lands over the weekend and saw no indication of that on the bullet. In the pics, its hard for me to tell if Im seeing a carbon ring in the throat, or wash out, and cracking. Itll help when I know what it is Im seeing. Ive kind of concluded that its washed out in the throat. I could sure be wrong, but when finding my lands by removing ejector, and cambering my dummy round, brand new case and bullet there was no indication of carbon buildup on the bullet. I seated deeper andvdeeper until bolt handle freely fell down, and no more little click at top of bolt lift.

 

[lancetkenyon]

Looks like bad fire cracking. Pressure and heat do that. I have seen 28 Noslers go in as fast as 400 rounds. You are in the 28 Nosler speed range. 3200 w. a 180 is a hot load for a 7STW.

Barrels are a consumable. You have used it for 8 years, I would plan on replacing it.

You could try JB Bore Paste and hope it smooths it out some. Might get a few more rounds down it.

 

[Tidesloe]

If it still looks like you have a carbon ring after all you've done to it, I've had excellent luck with letting a soaked patch sit in the throat for an hour or two with a penetrating oil such as pb blaster then rotating a brush slowly with a drill in there also soaked with the penetrating oil. Pretty effortless way of getting rid of it for me. Also, I think I'd do some work on the firecracked throat and lands with jb's to try and smooth it out once it's good and clean. Will more than likely lose your ejector marks after all of these things are accounted for. I really think with all of us recently getting borescopes, we're just seeing what was always there in our trusty rifles. I'm not ready to panic yet...

I havent spun it with a drill, but Ill do that and see if I can get anything. Ive just been spinning by hand. Not very productive but Ive thought I should still get something out

 

[Mram10us]

Have you shot it since your cleaning?
It looks like you got most of any carbon in the neck area as the reamer marks are mostly visable. Carbon in this area impinges on the neck not allowing complete bullet release and hence increased pressure. An old trick was to insert a bullet in a fired case. If it slips right in then the carbon ring in the neck was not the offender.
A carbon ring in the throat itself often can be seen as it leaves marks (scratches) on a bullet when fully inserted into the throat.
These bore cams truly are a godsend when examining before/during/and after cleaning.

On another note, is the ammunition showing the ejector marks different in any way than when it didn't have pressure indicators?
Any change in brass, powder, bullets or any other components could show an increase in pressure.
Also was the ammunition "older" when these indicators showed? Possibility of "cold weld" could also boost up the pressure.

Hope you nail it down.

MNBB brings up more good points. Regarding cold weld, take a few rounds and seat the bullet arother .010" into the case. If it is noticeably tight they might be cold welded.

 

[tankgijohn72]

The firecracking is pretty normal with big overbore cartridges. Have seen very similar in my 26 nosler and 300 norma. The ejector marks you are seeing are due to higher pressure. As a barrel wears in this manner your pressure/velocity will increase with the same loads. It is possible that it is a carbon ring causing some of your issues. Based off of some endurance testing that I have conducted, I tend to thing it is just a higher coefficient of friction caused by the firecracking that causes the higher pressure/velocity. What I observed is that after a thorough cleaning the very first round out of the tube would be a lower velocity and the rounds to follow were right back to where they were at prior to cleaning. If you plotted your velocity for every shot from new to 1,000 rounds (i realise you wont actually have velocity data for every round) you will see a steady increase in pressure/velocity in this cartridge. But, all that said, sounds like it is still shooting well. So I would clean it well and keep hunting.

 

[Timnterra]

I don't see carbon build up in the pictures, I do see some pretty bad fire cracking in that barrel. I would look into the Tubb's Final Finish bullets or JB bore paste to smooth out that rough bore.

 

[Tidesloe]

Looks like bad fire cracking. Pressure and heat do that. I have seen 28 Noslers go in as fast as 400 rounds. You are in the 28 Nosler speed range. 3200 w. a 180 is a hot load for a 7STW.

Barrels are a consumable. You have used it for 8 years, I would plan on replacing it.

You could try JB Bore Paste and hope it smooths it out some. Might get a few more rounds down it.

You are sure right about that. They are consumable, however I feel like I got very little use out of it. I'll do things a bit differently going forward. I will milk it out as long as I can, yes probable jb paste it, and then figure out what I wanna rebarrel to, in a LA magnum bolt face that wont be quite as hard on a barrel, as well as a load that wont be so hard. Now I understand these things arent meant for casual joy shooting, but are a specialized tool, which should be used in a very conservative manner
The rebarreling isnt so much the problem, but the 6 month waits on it are

 

[Timnterra]

I have a 22 creedmoor that has about the same number of rounds through it and the firecracking in it looks about like that. I shoot 88gr bullets around 3200 FPS out of it. I think the cost of moving heavy-for-caliber bullets fast is barrel life.

 

[milo-2]

I'd get some JB bore paste and some Kroil, make a creamy paste and work the first 6" of that barrel some. You'll never remove the cracks, no matter what you do, but maybe knock some high spots down.
I am under the assumption, when a barrel gets fire cracked that bad, crap gets into the cracks, and ultimately raises the steel around it, therefore constricting the bore, hence your pressure. You may have to back your charge off a little bit to get back to original velocities.