Bore scoping my leaded Mosin barrel

[Wolfdog91]

First time bore scoping so not 100% what I'm seeing, let me know how off I was on my assessment

[Hannibal]

Right now there's so much in the bore it's difficult to tell much except that it's badly leaded.
Check your Chore-Boy with a magnet before you use it. Some appears to be copper or brass but is actually steel with a wash applied. Wrap a few strands around a cleaning brush and scrub the lead out. In the past I used Kroil as well, cleaning solvent would work too.
It'll take some time, elbow grease and quite a bit of effort at first especially. Keep at it until you get the leading out. Then dry patch it a few times and re-evaluate the bore afterwards.
It's quite possible you had copper/powder fouling to begin with which can contribute to fouling issues as well. Your borescope will show you what's in there or not there along with any corrosion damage.

[johnho]

Agree with Hannibal. Way too much lead to determine much of anything about that bore. I shot some cast bullets through my 1903A3 and it was way leaded up in a short time. Took a long time to get it out. I also used a lot of kroil and let it sit overnight and continued brushing the next day. Repeated several times. First time using a borescope is a real eye opener.

[Dusty Bannister]

I agree with the others. It does not help that there appears to be a serious deposit of copper or jacket material in the bore. I also expect to see some pits when you finally get the barrel clean. Solvent, scrub, wipe, wet with solvent, wait and repeat. You may encounter the fouling is in layers and you have to work through each one of them to clean the next. If you use a really aggressive solvent that can attack the iron of the barrel, you will just make the pits bigger.

The second barrel seems to have a lot of chatter marks left after boring the barrel before cutting the rifling. That will likely continue to be a problem for the life of the barrel.

[Hannibal]

Didn't realize there was a second barrel in the video. Gave up looking at all the leading.

The second is fairly typical for a button rifled production barrel so far as the marks running parallel across the lands and grooves. A Savage for instance will often look quite a bit like that. The bore is drilled then the button is pulled through leaving the ridge and groove pattern ironed into the bore surface by the rifling button. It's also pretty common to see that type of corrosion damage on bores that weren't properly cleaned and oiled before storage. That's what the groups of pits and things that look like worm holes are. Corrosion damage. It won't help in the accuracy department or with fouling but on a hunting rifle that shoots 1-2 MOA anyway and doesn't get shot for long strings it won't really have any effect in a practical use sense. You've still got a fair amount of fouling in the corners of the grooves also which is what the black streaks are. It's possible it's even layers of carbon fouling and copper fouling but it's probably primarily carbon based on the appearance of it. If you want to get it all out, wrap a couple of cleaning patches around a worn bore brush and apply either JB Bore Paste or Losso to the patches. Stroke the entire bore a few times, switch to short strokes and concentrate more on the darker areas then stroke the whole bore 3-4 times. Patch it out good with solvent and dry patches. Then check your progress with your bore scope. Repeat as necessary.

[jdgabbard]

Right now there's so much in the bore it's difficult to tell much except that it's badly leaded.
Check your Chore-Boy with a magnet before you use it. Some appears to be copper or brass but is actually steel with a wash applied.

This. It appears that there is a bunch of fouling from copper or brass mixed in there. This barrel needs some elbow grease just to get it down to bare steel to see what you're working with. It may be caused by the copper and brass fouling, or it might be very badly pitted and not be conducive to shooting cast. It's all just a guess until you clean it and get it back down to the metal. Once that is done you'll be able to better tell. It could even be something that could be taken out with some valve seating compound and a jag with a tight patch. You're just not going to know until it is clean.

[405grain]

I would recommend that you use the copper Choir Boy to scrub out the lead fouling as described above, but once you've removed the lead you should do an electrolysis cleaning on your barrel to remove the copper, carbon, and rust fouling that is stripping lead off your bullets like a cheese grater. Get the bulk of the lead out before you try this so you won't die of old age waiting for the lead to come off. Because Mosin's were mostly used during the period of corrosive primers there could be some pitting under all that crud, but cleaning that stuff out of the bore could do nothing but improve it. I tried doing an electrolysis cleaning on an absolute sewer pipe of a Mauser barrel once, just to see how it would work. After two days of scrubbing the barrel was still as dark as a cave. So then I used a TIG rod as the electrode, plugged the chamber, stuffed a small plastic funnel in the muzzle, and filled the barrel with window cleaner (because it contains ammonia). I connected the rod and the barrel to an ordinary 9v battery and the window cleaner started to fizz right away.

I left the barrel like this for 4 hours. I poured out the liquid and it had turned black. When I pulled out the rod it was covered in black slimy crud. I ran some patches through the barrel and the first one was like evicting a slimy black jellyfish. All of the patches were coming out covered with black residue, but each subsequent patch had less and less. The bore was still dark, but it's condition was notably better. I decided to repeat the electrolysis cleaning process again the next day. After the second cleaning I ran patches through the barrel until they were coming out dirty, but dirty like one would expect from an ordinary barrel that requires cleaning. I then cleaned the barrel in the conventional way. Now the bore was bright and shiny. All of the horrible fouling had been completely removed, exposing a perfectly clean steel surface. It was now easy to see that the clean barrel had more pits and craters in it than the face of the Moon, and was completely useless as an actual barrel. Back then a brand new Mauser barrel was way cheaper than doing a re-bore, so that barrel went into the trash. It was a good learning experience though, and since then I've used a trickle charger to electrolysis clean and de-rust many machine parts. Do a Google search on "electrolysis barrel cleaning" and you'll get several pages of information on the process.

[Outer Rondacker]

Well good news! The only kinda fouling that I don’t see is from PC. Get to scrubbing you got a little bit of work ahead of you. You can do it!

[popper]

If the mosin cleans up, the crown should get fixed.

[Wolfdog91]

So that is some heavy lead and copper I'm seeing , mm interesting, will shouldn't be too bad 🥱 been wanting an excuse to try some of that iosso stuff then bench rest guys are always talking about

Sent from my motorola edge 5G UW (2021) using Tapatalk

[Wolfdog91]

I would recommend that you use the copper Choir Boy to scrub out the lead fouling as described above, but once you've removed the lead you should do an electrolysis cleaning on your barrel to remove the copper, carbon, and rust fouling that is stripping lead off your bullets like a cheese grater. Get the bulk of the lead out before you try this so you won't die of old age waiting for the lead to come off. Because Mosin's were mostly used during the period of corrosive primers there could be some pitting under all that crud, but cleaning that stuff out of the bore could do nothing but improve it. I tried doing an electrolysis cleaning on an absolute sewer pipe of a Mauser barrel once, just to see how it would work. After two days of scrubbing the barrel was still as dark as a cave. So then I used a TIG rod as the electrode, plugged the chamber, stuffed a small plastic funnel in the muzzle, and filled the barrel with window cleaner (because it contains ammonia). I connected the rod and the barrel to an ordinary 9v battery and the window cleaner started to fizz right away.

I left the barrel like this for 4 hours. I poured out the liquid and it had turned black. When I pulled out the rod it was covered in black slimy crud. I ran some patches through the barrel and the first one was like evicting a slimy black jellyfish. All of the patches were coming out covered with black residue, but each subsequent patch had less and less. The bore was still dark, but it's condition was notably better. I decided to repeat the electrolysis cleaning process again the next day. After the second cleaning I ran patches through the barrel until they were coming out dirty, but dirty like one would expect from an ordinary barrel that requires cleaning. I then cleaned the barrel in the conventional way. Now the bore was bright and shiny. All of the horrible fouling had been completely removed, exposing a perfectly clean steel surface. It was now easy to see that the clean barrel had more pits and craters in it than the face of the Moon, and was completely useless as an actual barrel. Back then a brand new Mauser barrel was way cheaper than doing a re-bore, so that barrel went into the trash. It was a good learning experience though, and since then I've used a trickle charger to electrolysis clean and de-rust many machine parts. Do a Google search on "electrolysis barrel cleaning" and you'll get several pages of information on the process.

Hasn't been taking out massive chunks like I keep hearing about


Sent from my motorola edge 5G UW (2021) using Tapatalk

[Hannibal]

Hasn't been taking out massive chunks like I keep hearing about


Sent from my motorola edge 5G UW (2021) using Tapatalk

Provide a new borescope image please. Something ain't right. There's enough lead in that barrel to make a 1oz sinker with. Wish I could spend a day with you. I bet we'd both learn some things.

PM me if you want. I've some vacation coming up and I've never seen Mississippi. That might be really cool.

[405grain]

I use more scrubbing pad than that. I wrapped the brush with the maximum amount that I could force through the barrel. If you can, try at least twice as much as in the photo. Also, some cleaning oil helps to prevent the brush from getting stuck. (Disclaimer: My cleaning rod is made from a 3ft long 1/4" brass rod so I can push pretty hard on it. Use your judgment with that aluminum cleaning rod - you want for the copper to scrape away at the lead, but you don't want to bend the rod either.)

[waksupi]

The Mosin bore is a real sewer. Good example of corrosive primer damage. Powder coating shouldn't be leaving any of that trash in a clean bore. The second rifle looks like last ditch manufacturing, get it out the door! The Mosins I have had all had real good bores, and would shoot into 1.5"

[Wolfdog91]

Provide a new borescope image please. Something ain't right. There's enough lead in that barrel to make a 1oz sinker with. Wish I could spend a day with you. I bet we'd both learn some things.

PM me if you want. I've some vacation coming up and I've never seen Mississippi. That might be really cool.

[Larry Gibson]

Most here are implying there's something inherently wrong with the bore of your MN but I'm going to stab a sacred cow here. I've shot traditional cast that were lubed and GC'd in some severely pitted/corroded bores including several MNs. I have never, ever gotten any leading close to that. In fact, with a proper alloy, lube, fit and load I've never, ever gotten any leading at all.

I have, however, gotten similar leading in rifles and handguns with excellent bores when testing various PC'd bullets. Not all rifles or handguns but enough that I still am sticking with traditional lube. It's not either rifle that is the problem, it is the PC.

[Hannibal]

So after viewing the latest video, you've made quite a bit of progress but you still have a lot of lead in the last 1/4 to 1/3rd of the bore.

Right now what I'm starting to see is a lot of corrosion damage. Even in the chamber walls. You're going to need to remove that before anything will have any chance to shoot accurately, cast or jacketed.

I'm going to suggest that you finish stripping out the lead first. You can try a brush that fits a bit tighter and the same amount of Chore-Boy or apply at least twice as much Chore-Boy to the same brush.

Once you get that all out you're going to need to get the corrosion removed. I normally don't recommend this but that bore is really corroded. Plug the bore with a foam ear plug and fill it full of CLR. That's Calcium Lime Rust remover. Let it sit for an hour. Brush and patch it out real well. Then do it again.

A word of caution : the CLR will damage any remaining bluing or patina on anything it gets on. Be careful or the outside of the barrel and action will not retain it's current appearance.

You've got a lot of effort ahead of you and it's going to take considerable time and patience also.

Please post another borescope image once you think you're done. Curious to see just how bad that corrosion damage is.

I respectfully disagree with Larry's assessment. I *think* your bore had a considerable amount of exfoliated corrosion in the bore which contributed considerably to the leading issue. No way of knowing for sure unless you happen to have a borescope image before you tried shooting cast. If I am correct about that, it would also make it exponentially more difficult to obtain an accurate bore slug as well.

[M-Tecs]

There are always exceptions to the rules. I have a 30/40 Krag owned by Edward Sherriff Curtis that the only way to describe the bore is it looks like a rattail file turned inside out. Personal I thought it was so bad it was unsafe to fire. The previous owner encouraged me to try his 125 grain Nosler Ballistic Tip load. It is a solid 1 moa for 5 shot groups. I've put a couple hundred rounds thru it and the 1 MOA is an average.

[Hannibal]

There are always exceptions to the rules. I have a 30/40 Krag owned by Edward Sherriff Curtis that the only way to describe the bore is it looks like a rattail file turned inside out. Personal I thought it was so bad it was unsafe to fire. The previous owner encouraged me to try his 125 grain Nosler Ballistic Tip load. It is a solid 1 moa for 5 shot groups. I've put a couple hundred rounds thru it and the 1 MOA is an average.

Well I'd say you won the mil-sup barrel lottery then. Congratulations!

[Hannibal]

Wolfdog, it makes no difference to me if you take my advice, someone else's, or your own. Either way you're gonna learn something you didn't know before.

That's what this forum should be about. Learning.