300 rum throat fouling

[Lefty7mmstw]

Hi all, I have noticed a bit of a dull look on the throat of my 300 rum for the last couple of cleanings. The last time out she fouled rather quickly and the fouling was hard to remove. I've gotten most of it out, but the throat is rather dull with a bit of a torn up look to it.

To the question.... is this likely fire cracking, or am I still needing to get more fouling from the bore?
Assuming it is fire cracking, is there any way to repair the rifle to get another few hundred sub moa rounds from her. The accuracy still hasn't fallen off in this rifle, but it likely will the way it was fouling in the throat. The rifling itself is in very good shape and is not even shallow at the origin. I don't hate the idea of a fresh barrel, but I sure hate the idea of retiring a good barrel early if I do not have to.

To answer one question already... I have no idea the round count on the rifle, other than I've had it for around 8 years and put somewhere around 100 rounds per year through it; I also bought it used.

Thanks in advance for any replies.
Lefty

 

[Dosh]

Lefty, perhaps try IOSSO bore cream working the throat. I've had good luck with it for that carbon ring. JB is a bit rough for that problem, but I've used it on a rough barrel. Don't forget the bore guide.

 

[Triple BB]

Might look at running some of Tubb's finishing bullets through it.

 

[Lefty7mmstw]

Lefty, perhaps try IOSSO bore cream working the throat. I've had good luck with it for that carbon ring. JB is a bit rough for that problem, but I've used it on a rough barrel. Don't forget the bore guide.

I've worked it a bit with jb already as the fouling was stubborn. I'll look at the Iosso to start with before really working it with jb....

 

[Lefty7mmstw]

Might look at running some of Tubb's finishing bullets through it.

That will likely be what I do if the Iosso and jb do not work. I'm hoping not to do much damage to the rifling itself as the rifle shoots well at present. I'm afraid gritted bullets may change the accuracy if they shallow the rifling out much. I may have unfounded fears, but I will likely use the Tubb's pills later as more of a last resort, so to speak.

 

[RockyMtnMT]

I think you stay the course. Keep shooting and cleaning as you are. Until accuracy becomes an issue. When that happens set the barrel back or re barrel it. Don't fix it if it aint broke.

Steve

 

[CogburnR]

One of the benefits that are claimed for treating barrels with hexagonal boron nitrite is much reduced fouling. The hbn doesn't stick to the bore and fouling doesn't stick to hbn.

I have some on order, claimed benefits are reduced extreme spread of velocities, cold bore shot in group, extended barrel life, reduced powder and copper fouling.

 

[Jokostel]

John...
Gotta remember, you're running a ****ton of SLOW powders in that thing....and one hell of a jump, with obvious reasons.
Carbon steel barrels that I have had, have always had this issue moreso than SS.
Buy a can of KranoKroil and SOAK the interior of the barrel with it overnight...
It's a microscopic oil that will get into the metallurgy... let alone underneath that damned carbon build. Hit it with a patch soaked in it again before you clean it.

I don't understand WHY people talk abrasive bullets,pastes...etc.
Think of it this way folks... if your engine is burning oil, do you take the heads off and scrape the cylinder walls with 60 grit sandpaper or a bastard file, in hopes of curing the issue?
Why would that be any different than a rifle barrel?
Barrels will do what they do, and for the most part, other than obvious issues... LEAVE THEM ALONE UNTIL THE ACCURACY CHANGES.

 

[elkaholic]

Hi Lefty.....I hate to say it but I think what you are seeing is normal throat erosion. You think that you have put approx. 800 rounds through it, plus it was used and there is no telling how many the previous owner fired. You probably do have carbon build up because a rough throat has a greater tendency to do that. I have had 3 300 rums and they are not known for good barrel life. I would shoot it until you are unhappy with accuracy but plan on a new barrel before long. Just my opinion.......Rich

 

[Lefty7mmstw]

Hi Lefty.....I hate to say it but I think what you are seeing is normal throat erosion. You think that you have put approx. 800 rounds through it, plus it was used and there is no telling how many the previous owner fired. You probably do have carbon build up because a rough throat has a greater tendency to do that. I have had 3 300 rums and they are not known for good barrel life. I would shoot it until you are unhappy with accuracy but plan on a new barrel before long. Just my opinion.......Rich

Hi Rich,
she looked great until the last couple of cleanings. Then she got a bit of haze to the throat area. This time she fouled rather badly. I did scrub the throat a bit with jb to get the fouling out, but it still has a bit of haze to it.

 

[Lefty7mmstw]

John...
Gotta remember, you're running a ****ton of SLOW powders in that thing....and one hell of a jump, with obvious reasons.
Carbon steel barrels that I have had, have always had this issue moreso than SS.
Buy a can of KranoKroil and SOAK the interior of the barrel with it overnight...
It's a microscopic oil that will get into the metallurgy... let alone underneath that damned carbon build. Hit it with a patch soaked in it again before you clean it.

I don't understand WHY people talk abrasive bullets,pastes...etc.
Think of it this way folks... if your engine is burning oil, do you take the heads off and scrape the cylinder walls with 60 grit sandpaper or a bastard file, in hopes of curing the issue?
Why would that be any different than a rifle barrel?
Barrels will do what they do, and for the most part, other than obvious issues... LEAVE THEM ALONE UNTIL THE ACCURACY CHANGES.

Hey back bro,
I did use jb just enough to get most of the fouling out after it was soaked with either hopes or kroil for a day or so each. I'll work it a bit tonight with a bronze brush and kroil and let her sit until I'm able to work with it again in a couple of days.

 

[bigngreen]

People use abrasives because it works and works very well when used properly. I like KG1 and lap the throat every 200 rounds on aggressive chamberings and it make a difference on accuracy life and jacket integrity. If you keep that throat smooth while it wears it real helps. Soaking barrels is a waste of your time, less than a minute, two patches and a few strokes each in the throat and pushed out and your done. Win Win!

 

[Lefty7mmstw]

People use abrasives because it works and works very well when used properly. I like KG1 and lap the throat every 200 rounds on aggressive chamberings and it make a difference on accuracy life and jacket integrity. If you keep that throat smooth while it wears it real helps. Soaking barrels is a waste of your time, less than a minute, two patches and a few strokes each in the throat and pushed out and your done. Win Win!

If a problem like the fast fouling I experienced comes up I'd say soaking with a creeping oil would help with carbon removal to assess the damage. I've already done this so it won't help to debate that.

I'm going to make sure the barrel is 100% fouling free, use a mild abrasive to massage the throat until it visibly improves, then assess accuracy. The rifling itself is in very good condition, so a bit of throat work shouldn't do much harm.

If the accuracy is sub par ( or I can not get the damage erased), I've got a 'smith lined up to do a set-back for a reasonable cost. I have to assess whether the action needs trueing first though. The rifle has a moderate issue with the top end alignment so I'll have to measure to find out where the miss-alignment is. I may be better off scrapping the barrel and replacing it.

 

[MagnumManiac]

Why are you so worried about your throat?
They erode, no matter how often you scrape it, polish it or any other thing you do to it, it WILL get larger and longer. How it looks has NO impact on accuracy, if it's dull that's because it has eroded and has haze cracking, normal wear, nothing more. What kills accuracy is how FAR it has eroded DOWN the barrel, increasing the LENGTH to the origin of the rifling.
How much has your velocity dropped with the SAME load over the last 8 years?
If it is substantial, say 150-200fps, then yes, your throat is eroded and accuracy will gradually lessen off, how much you ask, no body knows, but barrels just don't go 'bad' overnight.
BTW, the carbon ring is a good thing, it keeps your bullets straight!
I shoot comp in 200 round strings, never do I clean after a 60+ round match, never!!
I've seen more barrels ruined by excessive cleaning than I have from excessive shooting!!

Cheers.
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