Bore pics - what is this ?

Pitting....the barrel is 70 plus years old, clean it and shoot it if it works well dont worry about it, from what you stated it should work just fine for its intended purpose.
 
What kind of shape is the rifle in? Does it have clean original wood with factory but plate and are the sights in original condition? If it is a complete clean MOD70 in 375H&H and shoots ok enjoy it as a rare collectible and leave it as is.

Externally it looks in very good condition, the stock was original, it has a red butt from Winchester. It was cracked through the mag well between the action screws, I'm guessing because back then crossbolts were not in fashion. I had my gunsmith fix the crack, I think he injected epoxy and clamped it. I put it away and had a fiberglass stock made which I use now that adds some weight and it shoots well as you can hold with open sights. The rear sight is dovetailed just forward of the chamber, and was a bit loose, I put shim stock under it and it's tight again.

It came with only two holes in the front of the receiver, I had two put in the rear, but it's impossible to mount any bases on or over the receiver, so I just put the grub screws back in.

I've done one night of a Hoppes #9 soak, I have to go get and some Boretech.

The marks are clearly some sort of corrosion, it is definitely pitting.

This is the chamber, with fine pitting -

375H&H-3.jpg


This is towards the end of the barrel

375H&H-4.jpg


This is just ahead of the chamber

375H&H-5.jpg


I'll update after a few days of Boretech treatment.
 
I think if it were mine and I just wanted to shoot it I would just shoot it and do a light clean without removing the copper. The copper should fill the pits and prevent any more pitting. It would also increase the bore diameter a little, which could make it shoot better.

This is one place that a fouled barrel might be better.

J E CUSTOM
 
FiftyBMG, I am going to echo a lot of people here.. that is copper or brass monoliths or maybe lots of copper jacketed slugs going the barrel.
the rest might be carbon, rough barrel, or something other build up. I would hit it with my favorite combo Wipe out-patch out and wipe out- accelerator. accelerator first on a plastic brush, then patch out on a plastic brush. agitate for 5 to 10 minutes, let set for about 15 minutes and agitate for 5 minutes. then let sit for 15 minutes. then push a patch through. you will be amazed how much junk will pour or push out the barrel. then hit the barrel with a light oil soaked patch and then rub that patch in JB bore paste and see what kind of black comes out and how quickly. silvery is lead, charcoal is carbon, and something in between is a rough bore. My bet is Lead. that is from what I see and the age of the gun and the caliber. A lot of people loved putting big lead slugs down their 375 H&H's back int he 50's and 60's. I own a 1952 70 375 H&H, the bore was leaded up when I got it. I spent many hours with various cleaners getting that lead out. JB also played a part when I thought it was clean, a few strokes of BJ told me that I was not done yet.

I got a 1951-1952 30-06 that the barrel slugged out at 0.304". No, that is not a misprint/typo, the gun came in with primers popping out of the cases, severe pressure signs, from factory 150 grain slugs/ammo. it took me 3 weeks of Butches bore shine, Sweet's 7.62, and JB bore paste to get that one clean. the gun had never been cleaned since it was new. after all the build up was gone the gun shot extremely well.


After seeing the update picks.. I think I would send it off to get a new barrel put on.
 
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Externally it looks in very good condition, the stock was original, it has a red butt from Winchester. It was cracked through the mag well between the action screws, I'm guessing because back then crossbolts were not in fashion. I had my gunsmith fix the crack, I think he injected epoxy and clamped it. I put it away and had a fiberglass stock made which I use now that adds some weight and it shoots well as you can hold with open sights. The rear sight is dovetailed just forward of the chamber, and was a bit loose, I put shim stock under it and it's tight again.

It came with only two holes in the front of the receiver, I had two put in the rear, but it's impossible to mount any bases on or over the receiver, so I just put the grub screws back in.

I've done one night of a Hoppes #9 soak, I have to go get and some Boretech.

The marks are clearly some sort of corrosion, it is definitely pitting.

This is the chamber, with fine pitting -

View attachment 173742

This is towards the end of the barrel

View attachment 173743

This is just ahead of the chamber

View attachment 173744

I'll update after a few days of Boretech treatment.
Definitely pitting. You can now see the actual pits now that you removed the corrosion product that make the tiny 'bumps' at each pit. I agree with J.E. above, leaving the copper fouling in the barrel may be the best route. At least it will somewhat fill in the pits to a degree and make the surface less rough.
 
After two night in Boretech Eliminator.

375H&H-12.jpg


The ends of the barrel have cleaned up from the brass.

375H&H-13.jpg


The mid section still has some brass fouling, one more night should fix that.

375H&H-14.jpg


Some of the liquid pooled outside the muzzle while standing overnight, I now have a brasss front sight that I never knew I had before.
 
After two night in Boretech Eliminator.

375H&H-12.jpg


The ends of the barrel have cleaned up from the brass.

375H&H-13.jpg


The mid section still has some brass fouling, one more night should fix that.

375H&H-14.jpg


Some of the liquid pooled outside the muzzle while standing overnight, I now have a brasss front sight that I never knew I had before.
I would switch to JB bore paste at this time and knock those bumps out.
 
You're on the right track. As mentioned before, there could be lead too. Some JB next wouldn't hurt a thing. Do the Tubbs once you're sure you have it completely clean. Clean well during the Tubbs process. You'll be super pleased in the end. Can you share images of the throat and leade?
 
I agree with the other two above me. I would use JB bore paste on this barrel and see if more than half of all that irregularity we see is lead and carbon is out of this barrel.. you might find that about half of those bumps might go away and the barrel might be better than you think.
 
Your barrel surface resembles pictures of high sulphur steel. This sulphur content doesn't hurt anything in barrels and given the vintage may have come from wartime material stocks.

It doesn't look like it has been shot much and has a long life ahead of it.
 
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